build(phpstan): pin phpstan to v1 (#330)

pin phpstan to v1 as v2 is not compatible with our repo yet. should fix
failing checks in CI since PHPStan v2 release.

fixes INT-774

composer.json

@@ -37,7 +37,7 @@
         "nette/robot-loader": ">= 3",
         "pestphp/pest": ">= 1",
         "phpdocumentor/reflection-docblock": "^5",
-        "phpstan/phpstan": ">= 1",
+        "phpstan/phpstan": "^1",
         "rector/rector": ">= 1",
         "spatie/pest-plugin-snapshots": ">= 1",
         "symfony/console": "*"
@@ -72,4 +72,4 @@
             "pestphp/pest-plugin": true
         }
     }
-}
+}