Upgrade to actions/cache@v4 (#1228)

Author: dlqqq

.github/workflows/e2e-tests.yml

@@ -35,7 +35,7 @@ jobs:
         run: jlpm install
 
       - name: Set up browser cache
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         with:
           path: |
             ${{ github.workspace }}/pw-browsers