Add phpstan workflow

.github/workflows/phpstan.yml

@@ -0,0 +1,36 @@
+name: Run PHPStan
+
+on:
+  # Run on pushes to select branches and on all pull requests.
+  push:
+    branches:
+      - main
+      - develop
+      - 'release/[0-9]+.[0-9]+*'
+      - 'hotfix/[0-9]+.[0-9]+*'
+  pull_request:
+  # Allow manually triggering the workflow.
+  workflow_dispatch:
+
+jobs:
+  phpstan:
+    name: Static Analysis
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: 'latest'
+          coverage: none
+          tools: composer, cs2pr
+
+      - name: Install PHP dependencies
+        uses: ramsey/composer-install@v2
+        with:
+          composer-options: '--prefer-dist --no-scripts'
+
+      - name: PHPStan
+        run: composer phpstan