Update actions/cache action to v2.1.7

Author: renovate-bot

.github/workflows/ci.yml

@@ -42,7 +42,7 @@ jobs:
         run: echo "::set-output name=directory::$(composer config cache-dir)"
 
       - name: Cache composer dependencies
-        uses: actions/[email protected].3
+        uses: actions/[email protected].7
         with:
           path: ${{ steps.composer-cache.outputs.directory }}
           key: ${{ matrix.php }}-composer-${{ hashFiles('**/composer.lock') }}