COMP: Update ctkTest to use qWarning() instead of deprecated QTest::qWarn()

This fixes warnings like the following:

```
/path/to/CTK/Libs/Testing/ctkTest.h: In function ‘void ctkTest::mouseEvent(QTest::MouseAction, QWidget*, Qt::MouseButton, Qt::KeyboardModifiers, QPoint, int)’:
/path/to/CTK/Libs/Testing/ctkTest.h:98:12: warning: ‘void QTest::qWarn(const char*, const char*, int)’ is deprecated: Use qWarning() instead [-Wdeprecated-declarations]
   98 |     QTest::qWarn(qPrintable(warning.arg(mouseActionNames[static_cast<int>(action)])));
      |            ^~~~~
```

Author: jcfr

Libs/Testing/ctkTest.h

@@ -95,7 +95,7 @@ static void mouseEvent(QTest::MouseAction action, QWidget *widget, Qt::MouseButt
     static const char *mouseActionNames[] =
         { "MousePress", "MouseRelease", "MouseClick", "MouseDClick", "MouseMove" };
     QString warning = QString::fromLatin1("Mouse event \"%1\" not accepted by receiving widget");
-    QTest::qWarn(qPrintable(warning.arg(mouseActionNames[static_cast<int>(action)])));
+    qWarning() << qPrintable(warning.arg(mouseActionNames[static_cast<int>(action)]));
   }
 }