Upgrade to actions/cache@v4 for Shardy GitHub workflow.

Reference: actions/setup-node#1275
PiperOrigin-RevId: 748399822

Author: ZixuanJiang

.github/workflows/build_test_bazel.yml

@@ -42,7 +42,7 @@ jobs:
         uses: bazelbuild/setup-bazelisk@v2
 
       - name: Mount Bazel Cache
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: "~/.cache/bazel"
           key: ${{ runner.os }}-shardy_bazelbuild-${{ hashFiles('.bazelversion', '.bazelrc', 'WORKSPACE', 'WORKSPACE.bazel', 'MODULE.bazel') }}