Fix CI with new version of actions/cache

Author: keith

.github/workflows/ci.yml

@@ -26,7 +26,7 @@ jobs:
       - uses: actions/checkout@v2
 
       - name: Mount bazel cache
-        uses: actions/cache@v1
+        uses: actions/cache@v4
         with:
           path: "/home/runner/.cache/bazel"
           key: ${{ runner.os }}-bazel