FlightTab: Assisted flight fix

Booleans should be encoded as ints and not strings.
Why this worked with pyqt5 is still obscured but it looks like its been a change.
And regardless bools in other parts of this code is encoded as integers, so keeping it unified is a good idea

src/cfclient/ui/tabs/FlightTab.py

@@ -715,7 +715,7 @@ def _assisted_control_updated(self, enabled):
             self.targetHeight.setEnabled(enabled)
             print('Chaning enable for target height: %s' % enabled)
         else:
-            self._helper.cf.param.set_value("flightmode.althold", str(enabled))
+            self._helper.cf.param.set_value("flightmode.althold", int(enabled))
 
     def alt1_updated(self, state):
         if state: