CI: Update actions/cache to @4

Author: adamziel

.github/actions/prepare-playground/action.yml

@@ -9,7 +9,7 @@ runs:
         - uses: actions/setup-node@v3
         - name: Cache node modules
           id: cache-nodemodules
-          uses: actions/cache@v2
+          uses: actions/cache@v4
           env:
               cache-name: cache-node-modules
           with: