Switch to haskell/actions/setup.

Author: robrix

.github/workflows/haskell.yml

@@ -21,7 +21,7 @@ jobs:
     - uses: actions/checkout@v2
       if: github.event.action == 'opened' || github.event.action == 'synchronize' || github.event.ref == 'refs/heads/master'
 
-    - uses: actions/setup-haskell@v1
+    - uses: haskell/actions/setup@v1.2.2
       name: Setup Haskell
       with:
         ghc-version: ${{ matrix.ghc }}