Fix ghc-8.2

Author: phadej

tests/UnitTests.hs

@@ -64,7 +64,6 @@ import Test.Tasty.HUnit (Assertion, assertFailure, assertEqual, testCase, testCa
 import Text.Printf (printf)
 import UnitTests.NullaryConstructors (nullaryConstructors)
 import UnitTests.OptionalFields (optionalFields)
-import qualified Data.ByteString as S
 import qualified Data.ByteString.Base16.Lazy as LBase16
 import qualified Data.ByteString.Lazy.Char8 as L
 import qualified Data.Text.Lazy as LT

tests/UnitTests/OptionalFields/Manual.hs

@@ -1,10 +1,15 @@
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE RecordWildCards #-}
 {-# LANGUAGE TypeApplications #-}
 {-# OPTIONS_GHC -Wno-orphans #-}
 
 module UnitTests.OptionalFields.Manual (omitManual) where
 
+#if !MIN_VERSION_base(4,11,0)
+import Data.Semigroup ((<>))
+#endif
+
 import UnitTests.OptionalFields.Common
 
 instance ToJSON RecordA where