Fixes the following error
```
qdbusxml2cpp: Got unknown type `a{sv}' processing '/build/static-compat-syncthingtray/src/syncthingtray/syncthingconnector/org.freedesktop.DBus.Properties.xml'
You should add <annotation name="org.qtproject.QtDBus.QtTypeName.Out1" value="<type>"/> to the XML description for 'changed_properties'
```
by following the suggestion of that error. Not sure why this
error occurs only now. Maybe `qdbusxml2cpp` changed in Qt 6.5.0.