Fix tests for older GHCs

Author: ryantrinkle

test/tests.hs

@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE TemplateHaskell #-}
 module Main where
 
@@ -13,7 +14,12 @@ import Hedgehog.Range as Range ( linear )
 import Control.Monad (replicateM)
 import System.Exit (exitFailure, exitSuccess)
 import Data.Sequence as Seq ( foldMapWithIndex, replicateM )
-import Data.Semigroup (Sum (..))
+import Data.Semigroup
+  ( Sum (..)
+#if !MIN_VERSION_base(4,11,0)
+  , Semigroup(..)
+#endif
+  )
 
 main :: IO ()
 main = do