Cull language pragmas in main module

lib/Database/PostgreSQL/Opium.hs

@@ -1,10 +1,6 @@
-{-# LANGUAGE DataKinds #-}
-{-# LANGUAGE FlexibleContexts #-}
-{-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE LambdaCase #-}
-{-# LANGUAGE KindSignatures #-}
-{-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE TypeApplications #-}
 
 module Database.PostgreSQL.Opium

opium.cabal

@@ -52,7 +52,7 @@ build-type:         Simple
 -- extra-source-files:
 
 common warnings
-    ghc-options: -Wall
+    ghc-options: -Wall -Wextra
 
 library
     -- Import common warning flags.