Update dependency phpstan/phpstan to v1.12.6 (#26)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

composer.json

@@ -32,6 +32,6 @@
     },
     "require-dev": {
         "phpunit/phpunit": "^11.0",
-        "phpstan/phpstan": "1.11.9"
+        "phpstan/phpstan": "1.12.6"
     }
 }