Update .github/workflows/haskell-ci.yml

Co-authored-by: Neil Mayhew <[email protected]>

Author: MaximilianAlgehed

.github/workflows/haskell-ci.yml

@@ -24,7 +24,7 @@ jobs:
 
     strategy:
       matrix:
-        ghc-version: [latest, 9.12, "9.10", 9.8, 9.6]
+        ghc-version: ["9.12", "9.10", "9.8", "9.6"]
       fail-fast: false
 
     runs-on: ubuntu-latest