LibGUI: Fix move() of const StringView&

Author: https://github.com/deoxxa
Commit: aa95bd7037
Pull-request: https://github.com/SerenityOS/serenity/pull/565
Reviewed-by: https://github.com/awesomekling

Libraries/LibGUI/GLabel.cpp

@@ -29,7 +29,7 @@ void GLabel::set_text(const StringView& text)
 {
     if (text == m_text)
         return;
-    m_text = move(text);
+    m_text = text;
     update();
 }