test: run Node.js 16 tests case (#551)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **New Features**
- Introduced a new GitHub Actions workflow for automated continuous
integration in a Node.js 16 environment.
- Added a new testing script for Node.js 16 to enhance testing
capabilities.

- **Chores**
- Updated `package.json` to include the new `"test-node16"` script for
executing example Node.js scripts.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: fengmk2

.github/workflows/nodejs-16.yml

@@ -0,0 +1,23 @@
+name: Node.js 16 CI
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+      - name: Use Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '16.x'
+      - run: npm install
+      - run: npm run prepublishOnly
+      - run: node -v
+      - run: npm run test-node16 

package.json

@@ -38,6 +38,7 @@
     "test-tsc:esm": "cd test/fixtures/ts-esm && rm -rf node_modules && npm link ../../.. && npm run build",
     "test": "npm run lint && vitest run",
     "test-keepalive": "cross-env TEST_KEEPALIVE_COUNT=50 vitest run --test-timeout 180000 keep-alive-header.test.ts",
+    "test-node16": "node examples/httpclient.cjs && node examples/search_github.cjs && node examples/timing.cjs",
     "cov": "vitest run --coverage",
     "ci": "npm run lint && npm run cov && npm run prepublishOnly && npm pack && attw --pack",
     "clean": "rm -rf dist",