Enable cabal flaky test (#4263)

Author: soulomoon

plugins/hls-cabal-plugin/test/Main.hs

@@ -104,8 +104,7 @@ pluginTests =
                 expectNoMoreDiagnostics 1 hsDoc "typechecking"
                 cabalDoc <- openDoc "simple-cabal.cabal" "cabal"
                 expectNoMoreDiagnostics 1 cabalDoc "parsing"
-            , ignoreTestBecause "Testcase is flaky for certain GHC versions (e.g. 9.2.5). See #3333 for details." $ do
-                runCabalTestCaseSession "Diagnostics in .hs files from invalid .cabal file" "simple-cabal" $ do
+            , runCabalTestCaseSession "Diagnostics in .hs files from invalid .cabal file" "simple-cabal" $ do
                     hsDoc <- openDoc "A.hs" "haskell"
                     expectNoMoreDiagnostics 1 hsDoc "typechecking"
                     cabalDoc <- openDoc "simple-cabal.cabal" "cabal"