Move ghc-options in stack config and out of cabal file

postgrest.cabal

@@ -22,11 +22,6 @@ Flag CI
   Default:     False
 
 executable postgrest
-  if flag(ci)
-    ghc-options:       -Wall -W -Werror
-  else
-    ghc-options:       -Wall -W -O2
-
   main-is:             PostgREST/Main.hs
   default-extensions:  OverloadedStrings, ScopedTypeVariables, QuasiQuotes, LambdaCase
   default-language:    Haskell2010
@@ -80,11 +75,6 @@ executable postgrest
                      , PostgREST.Types
 
 library
-  if flag(ci)
-    ghc-options:       -Wall -W -Werror
-  else
-    ghc-options:       -Wall -W -O2
-
   default-language:    Haskell2010
   default-extensions:  OverloadedStrings, ScopedTypeVariables, QuasiQuotes
   build-depends:       aeson
@@ -136,10 +126,6 @@ Test-Suite spec
   Default-Language:    Haskell2010
   default-extensions:  OverloadedStrings, ScopedTypeVariables, QuasiQuotes, LambdaCase
   Hs-Source-Dirs:      test, src
-  if flag(ci)
-    ghc-options:       -Wall -W -Werror
-  else
-    ghc-options:       -Wall -W -O2
   Main-Is:             Main.hs
   Other-Modules:       Feature.AuthSpec
                      , Feature.CorsSpec