Add test action and lock Bazel version with Bazelisk

.bazeliskrc

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+USE_BAZEL_VERSION=8.5.1

.github/workflows/bazel-tests.yaml

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+name: Bazel Tests
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  test:
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v4
+      - uses: bazel-contrib/setup-bazel@0.18.0
+        with:
+          # Avoid downloading Bazel every time.
+          bazelisk-cache: true
+          # Store build cache per workflow.
+          disk-cache: ${{ github.workflow }}
+          # Share repository cache between workflows.
+          repository-cache: true
+      - name: Build with Bazel
+        run: bazel build //...
+      - name: Test with Bazel
+        run: bazel test //...