enable bench action for 9.6, 9.8

Author: soulomoon

.github/workflows/bench.yml

@@ -115,7 +115,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ghc: ['9.2', '9.4']
+        ghc: ['9.2', '9.4', '9.6', '9.8']
         os: [ubuntu-latest]
         cabal: ['3.10']
         example: ['cabal', 'lsp-types']