CI: Configure unit tests in CI

.github/workflows/tests.yml

@@ -0,0 +1,20 @@
+name: 'Run tests'
+
+on: [push, workflow_dispatch]
+
+jobs:
+  run-tests:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Setup node
+        uses: actions/setup-node@v4
+        with:
+#         TODO: add version to a .nvmrc or at least a variable
+          node-version: 18.12.1
+          cache: npm
+      - name: Install
+        run: npm ci
+      - name: Run tests
+        run: npm run test:unit