[ci] add compat test

Author: TomasVotruba

.github/workflows/compat_test.yaml

@@ -0,0 +1,31 @@
+# builds the content of https://github.com/rectorphp/rector
+# inspiration from https://github.com/phpstan/phpstan-src/blob/master/.github/workflows/phar.yml
+name: PHPUnit and PHPStan Compat Test
+
+on:
+    push:
+        branches:
+            - main
+
+jobs:
+    build_scoped_rector:
+        runs-on: ubuntu-latest
+        timeout-minutes: 3
+
+        steps:
+            -
+                uses: actions/checkout@v4
+                with:
+                    fetch-depth: 0
+
+            -
+                uses: shivammathur/setup-php@v2
+                with:
+                    php-version: 8.2
+                    coverage: none
+
+            - run:
+                composer create-project rector/rector-compat-tests:dev-main .
+                vendor/bin/phpunit tests/PHPStan
+                vendor/bin/phpunit tests/PHPUnit
+                vendor/bin/phpunit tests