Fix after PHPStan update

Newest version of PHPStan complains about `@return $this`.

Author: otsch

src/Query.php

@@ -890,7 +890,7 @@ private function firstOrLast(?string $key = null, bool $first = true): mixed
 
     /**
      * @param string|mixed[] $query
-     * @return $this
+     * @return self
      * @throws Exception
      */
     private function newWithSameSettings(string|array $query): self