fix(capslockindicator): also update indicator when the app gets focus

This allows to have an up-to-date indicator when the caps lock state
changed outside of the application and the user comes back to it, even
if it doesn't trigger a Show event (e.g. the window was visible all the
time).

src/widget/capslockindicator.cpp

@@ -36,6 +36,7 @@ bool CapsLockIndicator::eventFilter(QObject *obj, QEvent *event)
         if (obj == this)
             updateIndicator();
         break;
+    case QEvent::WindowActivate:
     case QEvent::KeyRelease:
         updateIndicator();
         break;