manager: fix missing return

Add a missing return statement at end of Manager::detachLocalParticipant().

Change-Id: I7b83403340aaa425ba0641741f9a65953c253253
Reviewed-by: Anthony Léonard <anthony.leonard@savoirfairelinux.com>

src/manager.cpp

@@ -1520,6 +1520,7 @@ Manager::detachLocalParticipant()
     emitSignal<DRing::CallSignal::ConferenceChanged>(conf->getConfID(), conf->getStateStr());
 
     pimpl_->unsetCurrentCall();
+    return true;
 }
 
 bool