Stack CI: bump actions to latest versions

Author: andreasabel

.github/workflows/stack.yml

@@ -22,7 +22,7 @@ jobs:
             ghc: '9.12'
 
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
 
     - uses: haskell-actions/setup@v2
       id: setup
@@ -32,7 +32,7 @@ jobs:
         cabal-update: false
 
     - name: Restore cache
-      uses: actions/cache/restore@v4
+      uses: actions/cache/restore@v5
       id: cache
       env:
         key: ${{ runner.os }}-stack-${{ steps.setup.outputs.stack-version }}-ghc-${{ steps.setup.outputs.ghc-version }}
@@ -56,7 +56,7 @@ jobs:
       run:  stack test --stack-yaml=stack-${{ matrix.ghc }}.yaml --system-ghc
 
     - name: Save cache
-      uses: actions/cache/save@v4
+      uses: actions/cache/save@v5
       if: always()
       with:
         key: ${{ steps.cache.outputs.cache-primary-key }}