DBusHelper can throw a 'dbus.exceptions.DBusException'

and we don't want to import dbus here to match the specific exception type,
so let the linters whine about it

xpra/platform/posix/keyboard.py

@@ -46,7 +46,8 @@ def init_vars(self) -> None:
         self.__input_sources: dict[str, int] = {}
         try:
             self.__dbus_helper = DBusHelper()
-        except ImportError as e:
+            # we really want to catch `dbus.exceptions.DBusException` here instead:
+        except Exception as e:
             self.__dbus_helper = None
             log.info(f"gnome input sources requires dbus: {e}")
         else: