Upgrade the actions for Shardy GitHub workflow.

* bazelbuild/setup-bazelisk: v2 -> v3
* actions/cache: v3 -> v4

Reference: actions/setup-node#1275
PiperOrigin-RevId: 748431777

Author: ZixuanJiang

.github/workflows/build_test_bazel.yml

@@ -39,10 +39,10 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Setup Bazelisk
-        uses: bazelbuild/setup-bazelisk@v2
+        uses: bazelbuild/setup-bazelisk@v3
 
       - 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') }}