Revert "Extend support-window to accomodate GHC HEAD which has been b…

…umped to v8.7"

This reverts commit 3b98a57.

Cabal/Distribution/Simple/GHC.hs

@@ -136,11 +136,11 @@ configure verbosity hcPath hcPkgPath conf0 = do
       (userMaybeSpecifyPath "ghc" hcPath conf0)
   let implInfo = ghcVersionImplInfo ghcVersion
 
-  -- Cabal currently supports ghc >= 7.0.1 && < 8.8
-  unless (ghcVersion < mkVersion [8,8]) $
+  -- Cabal currently supports ghc >= 7.0.1 && < 8.7
+  unless (ghcVersion < mkVersion [8,7]) $
     warn verbosity $
          "Unknown/unsupported 'ghc' version detected "
-      ++ "(Cabal " ++ display cabalVersion ++ " supports 'ghc' version < 8.8): "
+      ++ "(Cabal " ++ display cabalVersion ++ " supports 'ghc' version < 8.7): "
       ++ programPath ghcProg ++ " is version " ++ display ghcVersion
 
   -- This is slightly tricky, we have to configure ghc first, then we use the