test(spec): inline config into test suite

Previously, information about each test-suite was repeated in 3 separate
places:
- as a label and as implicit knowledge in the test-suite itself,
- as a comment in Main.hs, and
- as a configuration in SpecHelper.hs.

With this change, there will be a single source of truth in the test
suite itself. This will allow a single test-suite to easily test
multiple different configurations.

test/spec/Feature/Query/UnicodeSpec.hs

@@ -1,17 +1,18 @@
 module Feature.Query.UnicodeSpec where
 
-import Network.Wai (Application)
-
+import Data.List.NonEmpty  (fromList)
 import Network.HTTP.Types
 import Test.Hspec
 import Test.Hspec.Wai
 import Test.Hspec.Wai.JSON
 
+import PostgREST.Config (AppConfig (..))
+
 import Protolude  hiding (get)
 import SpecHelper
 
-spec :: SpecWith ((), Application)
-spec =
+spec :: SpecWithConfig
+spec withConfig = withConfig (baseCfg { configDbSchemas = fromList ["تست"] }) $
   describe "Reading and writing to unicode schema and table names" $
     it "Can read and write values" $ do
       get "/%D9%85%D9%88%D8%A7%D8%B1%D8%AF"