CI: use haskell/actions/setup v2 [skip ci]

Author: LaurentRDC

.github/workflows/ci.yml

@@ -31,7 +31,7 @@ jobs:
     - uses: actions/checkout@v2
 
     - name: Install cabal/ghc
-      uses: haskell/actions/setup@v1
+      uses: haskell/actions/setup@v2
       id: setup-haskell
       with:
         ghc-version: ${{ matrix.ghc-version }}