T5677 test doesn't work on GitHub actions windows

cabal-testsuite/PackageTests/Regression/T5677/cabal.test.hs

@@ -2,4 +2,5 @@ import Test.Cabal.Prelude
 main = cabalTest $ do
   -- -Wmissing-export-lists is new in 8.4.
   skipUnless =<< ghcVersionIs (>= mkVersion [8,3])
+  skipIf =<< isWindows -- TODO: https://github.com/haskell/cabal/issues/6271
   cabal "v2-build" ["all"]