Fix a crash when showing tooltips

Looks like we have omitter Q_OBJECT declaration in
subclasses of TipLabel. This probably confuses
accessibility support in Qt 6, as it reads the classname
of the object. Apparently, the classname wasn't set
properly.

Task-number: QTCREATORBUG-24839
Change-Id: I5085e924fb3fa3a0f06d17372c7dc339db30226c
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/libs/utils/tooltip/tips.h

@@ -61,6 +61,7 @@ using TextItem = std::pair<QString, Qt::TextFormat>;
 
 class TextTip : public TipLabel
 {
+    Q_OBJECT
 public:
     TextTip(QWidget *parent);
 
@@ -80,6 +81,7 @@ private:
 
 class ColorTip : public TipLabel
 {
+    Q_OBJECT
 public:
     ColorTip(QWidget *parent);