Need to cabal update after cache unpack

Thanks @fgaz!

See also https://github.com/haskell-actions/setup?tab=readme-ov-file#model-cabal-workflow-with-caching

.github/workflows/haskell.yml

@@ -12,11 +12,14 @@ jobs:
 
     name: GHC ${{ matrix.ghc }} on ${{ matrix.os }}
     steps:
+
     - uses: actions/checkout@v3
+
     - uses: haskell-actions/setup@v2
       with:
         ghc-version: ${{ matrix.ghc }}
         cabal-version: '3.10.3.0'
+
     - name: Cache
       uses: actions/cache@v3
       env:
@@ -31,11 +34,16 @@ jobs:
           ${{ runner.os }}
 
     - name: Install dependencies
-      run: cabal build --only-dependencies --enable-tests --enable-benchmarks
+      run: |
+        cabal update
+        cabal build --only-dependencies --enable-tests --enable-benchmarks
+
     - name: Build
       run: cabal build --enable-tests --enable-benchmarks all
+
     - name: Run tests
       run: cabal test --enable-tests all
+
     - if: matrix.ghc != '8.4.4'
       # docs aren't built on ghc 8.4.4 because some dependency docs don't build on older GHCs
       name: Build Docs