Skip extensions cache if there are no extensions to install

.github/actions/ci-setup/action.yml

@@ -20,6 +20,7 @@ runs:
   using: composite
   steps:
     - name: Setup cache environment
+      if: ${{ inputs.php-extensions }}
       id: extcache
       uses: shivammathur/cache-extensions@v1
       with:
@@ -27,7 +28,8 @@ runs:
         extensions: ${{ inputs.php-extensions }}
         key: ${{ inputs.extensions-cache-key }}
     - name: Cache extensions
-      uses: actions/cache@v3
+      if: ${{ inputs.php-extensions }}
+      uses: actions/cache@v4
       with:
         path: ${{ steps.extcache.outputs.dir }}
         key: ${{ steps.extcache.outputs.key }}