phpstan: Upgrade to version 2

https://github.com/phpstan/phpstan/blob/2.1.x/UPGRADING.md

Required also bumping Rector since it uses PHPStan internally.

rector.php

@@ -3,29 +3,16 @@
 declare(strict_types=1);
 
 use Rector\Config\RectorConfig;
-use Rector\Core\ValueObject\PhpVersion;
 use Rector\Set\ValueObject\LevelSetList;
 
-return static function (RectorConfig $rectorConfig): void {
-    // paths to refactor; solid alternative to CLI arguments
-    $rectorConfig->paths([
+return RectorConfig::configure()
+    ->withPaths([
         __DIR__ . '/src',
         __DIR__ . '/tests',
-    ]);
-
-    // Path to phpstan with extensions, that PHPSTan in Rector uses to determine types
-    $rectorConfig->phpstanConfig(__DIR__ . '/phpstan.neon');
-
-    $rectorConfig->bootstrapFiles([
+    ])
+    ->withBootstrapFiles([
         __DIR__ . '/vendor/bin/.phpunit/phpunit/vendor/autoload.php',
         __DIR__ . '/vendor/autoload.php',
-    ]);
-
-    // Define what rule sets will be applied
-    $rectorConfig->sets([
-        LevelSetList::UP_TO_PHP_74,
-    ]);
-
-    // is your PHP version different from the one your refactor to?
-    $rectorConfig->phpVersion(PhpVersion::PHP_74);
-};
+    ])
+    ->withSets([LevelSetList::UP_TO_PHP_74])
+;