fix(ui): Att void for setStyleSheet

Signed-off-by: Collecting <collecting@noreply.localhost>

src/citron/game_list_p.h

@@ -430,6 +430,7 @@ public:
 
     void clear();
     void setFocus();
+    void setStyleSheet(const QString& sheet);
 
 private:
     void changeEvent(QEvent*) override;