Fix up and flesh out transaction validation specs

These didn't include phone or email, both of which are required.

spec/models/solidus_paypal_braintree/transaction_spec.rb

@@ -6,7 +6,9 @@
       {
         nonce: 'abcde-fghjkl-lmnop',
         payment_method: SolidusPaypalBraintree::Gateway.new,
-        payment_type: 'ApplePayCard'
+        payment_type: 'ApplePayCard',
+        phone: "555-1234",
+        email: "[email protected]"
       }
     end
 
@@ -33,5 +35,15 @@
       let(:valid_attributes) { super().except(:payment_type) }
       it { is_expected.to be false }
     end
+
+    context 'no phone' do
+      let(:valid_attributes) { super().except(:phone) }
+      it { is_expected.to be false }
+    end
+
+    context 'no email' do
+      let(:valid_attributes) { super().except(:email) }
+      it { is_expected.to be false }
+    end
   end
 end