Upgrade actions/cache to v5 to fix Node.js 20 deprecation warning

Author: andreagrandi

.github/workflows/ci.yml

@@ -116,7 +116,7 @@ jobs:
           npm run build:css
 
       - name: Cache Playwright browsers
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         with:
           path: ~/.cache/ms-playwright
           key: playwright-${{ hashFiles('requirements.txt') }}