use maintained Haskell action https://github.com/haskell/actions/tree/main/setup (#447)

Author: peterbecich

.github/workflows/ci.yml

@@ -19,7 +19,7 @@ jobs:
 
     - uses: actions/checkout@v2
 
-    - uses: actions/setup[email protected]
+    - uses: haskell/actions/setup@v2
       name: Setup Haskell Stack
       with:
         ghc-version: ${{ matrix.ghc }}