add: CI using github actions

.github/workflows/tests.yaml

@@ -0,0 +1,25 @@
+# From https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-nodejs#using-the-nodejs-starter-workflow
+name: Node.js and Solana CI
+
+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
+
+      # Install everything
+      - run: npm ci
+
+      # Run tests
+      - run: npm test