Use separate Spago config for tests

This will allow us to get the licenses of production dependencies only.
See my next commit.

package.json

@@ -35,7 +35,7 @@
     "build": "spago build && npm run esbuild && node copy",
     "prepack": "spago build && npm run esbuild:node",
     "server": "live-server web --open",
-    "test": "spago test"
+    "test": "spago -x test.dhall test"
   },
   "bugs": {
     "url": "https://github.com/sharkdp/insect/issues"

spago.dhall

@@ -5,12 +5,10 @@ Need help? See the following resources:
 -}
 { name = "insect"
 , dependencies =
-  [ "aff"
-  , "arrays"
+  [ "arrays"
   , "bifunctors"
   , "control"
   , "decimals"
-  , "effect"
   , "either"
   , "foldable-traversable"
   , "integers"
@@ -22,9 +20,8 @@ Need help? See the following resources:
   , "prelude"
   , "quantities"
   , "strings"
-  , "test-unit"
   , "tuples"
   ]
 , packages = ./packages.dhall
-, sources = [ "src/**/*.purs", "test/**/*.purs" ]
+, sources = [ "src/**/*.purs" ]
 }

test.dhall

@@ -0,0 +1,5 @@
+let conf = ./spago.dhall
+in conf // {
+  sources = conf.sources # [ "test/**/*.purs" ]
+, dependencies = conf.dependencies # ["aff", "effect", "test-unit"]
+}