Add a basic Github workflow file

The file is from VS Code's CI documentation:
https://code.visualstudio.com/api/working-with-extensions/continuous-integration#github-actions.
I'll add to it with specific issues to implement linting, packaging,
etc.

closes #5

.github/workflows/main.yaml

@@ -0,0 +1,24 @@
+name: Node.js CI
+
+on:
+ workflow_dispatch:
+ push:
+ pull_request:
+
+jobs:
+ build:
+ strategy:
+ matrix:
+ os: [macos-latest, ubuntu-latest, windows-latest]
+ runs-on: ${{matrix.os}}
+ steps:
+ - uses: actions/checkout@v3
+ - name: Install Node.js
+ uses: actions/setup-node@v3
+ with:
+ node-version: 16.x
+ - run: npm install
+ - run: xvfb-run --auto-servernum npm test
+ if: runner.os == 'Linux'
+ - run: npm test
+ if: runner.os != 'Linux'