Replace spree_put with put in controller tests

This removes the following annoying deprecation warnings that happen in
each test.

```
DEPRECATION WARNING: You are trying to generate the URL for a named route called :main_app but no such route was found. In the future, this will result in an `ActionController::UrlGenerationError` exception. (called from process_action_with_route at /usr/s
rc/app/spec/support/controller_requests_helper.rb:49)
DEPRECATION WARNING: Passing the `use_route` option in functional tests are deprecated. Support for this option in the `process` method (and the related `get`, `head`, `post`, `patch`, `put` and `delete` helpers) will be removed in the next version without
 replacement. Functional tests are essentially unit tests for controllers and they should not require knowledge to how the application's routes are configured. Instead, you should explicitly pass the appropiate params to the `process` method. Previously th
e engines guide also contained an incorrect example that recommended using this option to test an engine's controllers within the dummy application. That recommendation was incorrect and has since been corrected. Instead, you should override the `@routes`
variable in the test case with `Foo::Engine.routes`. See the updated engines guide for details. (called from process_action_with_route at /usr/src/app/spec/support/controller_requests_helper.rb:49)
```

spec/controllers/admin/variant_overrides_controller_spec.rb

@@ -21,7 +21,7 @@
         end
 
         it "redirects to unauthorized" do
-          spree_put :bulk_update, format: format, variant_overrides: variant_override_params
+          put :bulk_update, format: format, variant_overrides: variant_override_params
           expect(response).to redirect_to unauthorized_path
         end
       end
@@ -33,15 +33,15 @@
 
         context "but the producer has not granted VO permission" do
           it "redirects to unauthorized" do
-            spree_put :bulk_update, format: format, variant_overrides: variant_override_params
+            put :bulk_update, format: format, variant_overrides: variant_override_params
             expect(response).to redirect_to unauthorized_path
           end
 
           it 'only authorizes the updated variant overrides' do
             other_variant_override = create(:variant_override, hub: hub, variant: create(:variant))
             expect(controller).not_to receive(:authorize!).with(:update, other_variant_override)
 
-            spree_put :bulk_update, format: format, variant_overrides: variant_override_params
+            put :bulk_update, format: format, variant_overrides: variant_override_params
           end
         end
 
@@ -51,15 +51,16 @@
           end
 
           it "loads data" do
-            spree_put :bulk_update, format: format, variant_overrides: variant_override_params
+            put :bulk_update, format: format, variant_overrides: variant_override_params
             expect(assigns[:hubs]).to eq [hub]
             expect(assigns[:producers]).to eq [variant.product.supplier]
             expect(assigns[:hub_permissions]).to eq Hash[hub.id, [variant.product.supplier.id]]
             expect(assigns[:inventory_items]).to eq [inventory_item]
           end
 
           it "allows me to update the variant override" do
-            spree_put :bulk_update, format: format, variant_overrides: variant_override_params
+            put :bulk_update, format: format, variant_overrides: variant_override_params
+
             variant_override.reload
             expect(variant_override.price).to eq 123.45
             expect(variant_override.count_on_hand).to eq 321
@@ -71,7 +72,7 @@
             let(:variant_override_params) { [{ id: variant_override.id, price: "", count_on_hand: "", default_stock: nil, resettable: nil, sku: nil, on_demand: nil }] }
 
             it "destroys the variant override" do
-              spree_put :bulk_update, format: format, variant_overrides: variant_override_params
+              put :bulk_update, format: format, variant_overrides: variant_override_params
               expect(VariantOverride.find_by(id: variant_override.id)).to be_nil
             end
           end
@@ -83,7 +84,7 @@
             before { deleted_variant.update_attribute :deleted_at, Time.zone.now }
 
             it "allows to update other variant overrides" do
-              spree_put :bulk_update, format: format, variant_overrides: variant_override_params
+              put :bulk_update, format: format, variant_overrides: variant_override_params
 
               expect(response).to_not redirect_to unauthorized_path
               variant_override.reload
@@ -117,7 +118,7 @@
         end
 
         it "redirects to unauthorized" do
-          spree_put :bulk_reset, params
+          put :bulk_reset, params
           expect(response).to redirect_to unauthorized_path
         end
       end
@@ -129,7 +130,7 @@
 
         context "where the producer has not granted create_variant_overrides permission to the hub" do
           it "restricts access" do
-            spree_put :bulk_reset, params
+            put :bulk_reset, params
             expect(response).to redirect_to unauthorized_path
           end
         end
@@ -138,7 +139,7 @@
           let!(:er1) { create(:enterprise_relationship, parent: producer, child: hub, permissions_list: [:create_variant_overrides]) }
 
           it "loads data" do
-            spree_put :bulk_reset, params
+            put :bulk_reset, params
             expect(assigns[:hubs]).to eq [hub]
             expect(assigns[:producers]).to eq [producer]
             expect(assigns[:hub_permissions]).to eq Hash[hub.id, [producer.id]]
@@ -148,7 +149,7 @@
           it "updates stock to default values where reset is enabled" do
             expect(variant_override1.reload.count_on_hand).to eq 5 # reset enabled
             expect(variant_override2.reload.count_on_hand).to eq 2 # reset disabled
-            spree_put :bulk_reset, params
+            put :bulk_reset, params
             expect(variant_override1.reload.count_on_hand).to eq 7 # reset enabled
             expect(variant_override2.reload.count_on_hand).to eq 2 # reset disabled
           end
@@ -163,7 +164,7 @@
 
             it "does not reset count_on_hand for variant_overrides not in params" do
               expect {
-                spree_put :bulk_reset, params
+                put :bulk_reset, params
               }.to_not change{ variant_override3.reload.count_on_hand }
             end
           end