Enable -Wall -Wcompat -Werror in CI

src/Trace/Hpc/Combine.hs

@@ -5,10 +5,6 @@
 -- License            : BSD-3-Clause
 module Trace.Hpc.Combine (combinePlugin) where
 
-import Control.DeepSeq
-import Control.Monad
-import qualified Data.Map as Map
-import qualified Data.Set as Set
 import Trace.Hpc.Flags
 import Trace.Hpc.Plugin
 import Trace.Hpc.Tix