Prevent explicit nullable type warning on modern PHP (#815)

* Make param type explicityly nullable

* Actually, remove superflous arguments

Author: JeroenDeDauw

src/MapsHooks.php

@@ -115,7 +115,7 @@ public static function onRegisterTags( array &$tags ) {
 		return true;
 	}
 
-	public static function onChangeTagsAllowedAdd( array &$allowedTags, array $tags, \User $user = null ) {
+	public static function onChangeTagsAllowedAdd( array &$allowedTags ) {
 		$allowedTags[] = 'maps-visual-edit';
 	}