Ensure text return type consistency in TextNode::text method

Author: mr-chetan

src/PHPHtmlParser/Dom/Node/TextNode.php

@@ -104,10 +104,10 @@ public function text(): string
             // remember the conversion
             $this->convertedText = $text;
 
-            return $text;
+            return (string) $text;
         }
 
-        return $text;
+        return (string) $text;
     }
 
     /**