Update actions/cache action to v6

Author: renovate[bot]

.github/actions/cache-common-images/action.yml

@@ -5,7 +5,7 @@ runs:
   steps:
     - name: Set up GHA cache
       id: cache
-      uses: actions/cache@v5
+      uses: actions/cache@v6
       with:
         path: cached_images.tar
         key: ${{ runner.os }}-cache