Appease -Werror=type-equality-requires-operators

GHC 9.4 complains:

    The use of ‘~’ without TypeOperators
    will become an error in a future GHC release.

XMonad/Layout/Groups/Examples.hs

@@ -1,5 +1,8 @@
 {-# OPTIONS_GHC -fno-warn-missing-signatures #-}
-{-# LANGUAGE MultiParamTypeClasses, Rank2Types, TypeFamilies #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE Rank2Types #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE TypeOperators #-}
 
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