GitHub action for PHPstan CI

.github/workspaces/ci.yml

@@ -0,0 +1,16 @@
+name: CI
+run-name: ${{ github.actor}} runs CI
+
+on: [push]
+
+jobs:
+  phpstan:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: php-actions/composer@v6
+
+      - name: PHPStan Static Analysis
+        uses: php-actions/phpstan@v3
+        with:
+          path: src/