Add Test github action

Trying out a GitHub template, modified to run the test script

.github/workflows/tests.yml

@@ -0,0 +1,28 @@
+name: T
+
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main" ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [ 20.x ]
+
+    steps:
+    - uses: actions/checkout@v3
+
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v3
+      with:
+        node-version: ${{ matrix.node-version }}
+
+    - name: Test
+      run: |
+        yarn install --frozen-lockfile
+        yarn run test