Effects: Basic: LANGUAGE: rm unused FlexibleInstances

Author: Anton-Latukha

src/Nix/Effects/Basic.hs

@@ -2,7 +2,6 @@
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE ConstraintKinds #-}
 {-# LANGUAGE FlexibleContexts #-}
-{-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE ScopedTypeVariables #-}