add CI

.github/workflows/ci.yaml

@@ -0,0 +1,21 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+  workflow_dispatch:
+
+jobs:
+  ci:
+    name: Build & Test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Build
+        run: swift build --build-tests
+
+      - name: Run Tests
+        run: swift test