ci: run the test suite on pull requests

Tests only ran inside the publish job on push to master, so a broken
suite was first seen after merge and blocked the release.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Author: marceloprerender

.github/workflows/test.yml

@@ -0,0 +1,32 @@
+name: Test
+
+on:
+  pull_request:
+    branches:
+      - master
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v5
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Setup test dependencies
+        run: |
+          cd test/support/express3 && npm install
+          cd ../express4 && npm install
+
+      - name: Run tests
+        run: npm test