CI fixes

src/Monolog/Level.php

@@ -1,4 +1,13 @@
-<?php
+<?php declare(strict_types=1);
+
+/*
+ * This file is part of the Monolog package.
+ *
+ * (c) Jordi Boggiano <j.boggiano@seld.be>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
 
 namespace Monolog;
 
@@ -97,7 +106,6 @@ enum Level: int
     }
 
     /**
-     * @return string
      * @phpstan-return \Psr\Log\LogLevel::*
      */
     public function toPsrLogLevel(): string