revert: remove PHPStan GitHub Action

No version of saschaegerer/phpstan-typo3 bridges phpstan ^2 and TYPO3 ^12.4,
making automated PHPStan analysis via GitHub Actions not feasible at this time.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: fpodschwadek

.github/workflows/phpstan.yml

@@ -29,7 +29,6 @@
     "codeception/module-asserts": "*",
     "codeception/module-db": "^3.2",
     "codeception/verify": "^3.2",
-    "phpstan/phpstan": "^2",
     "ssch/typo3-rector": "^3.8",
     "typo3/coding-standards": "^0.8.0",
     "a9f/typo3-fractor": "^0.5.0"
@@ -45,9 +44,6 @@
     }
   },
   "config": {
-    "allow-plugins": true,
-    "audit": {
-      "ignore": ["PKSA-y2cr-5h3j-g3ys"]
-    }
+    "allow-plugins": true
   }
 }