Update ci.yml

Author: rct225

.github/workflows/ci.yml

@@ -26,7 +26,7 @@ jobs:
       - uses: actions/checkout@v2
 
       - name: Restore bundle cache
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         with:
           path: vendor/bundle
           key: ${{ runner.os }}-gems-${{ hashFiles('**/Gemfile.lock') }}