modify arguments of Dispatcher.announce_update

- 'pname' argument is not needed
- change 'modulename' argument to 'moduleobj'
  (needed for further change)

Change-Id: Ib21f8ad06d9b2be4005ff3513088a85e29785c94
Reviewed-on: https://forge.frm2.tum.de/review/c/secop/frappy/+/32744
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>

frappy/modules.py

@@ -946,6 +946,9 @@ class Attached(Property):
             if not modulename:
                 return None  # happens when mandatory=False and modulename is not given
             modobj = obj.secNode.get_module(modulename)
+            if not modobj:
+                raise ConfigError(f'attached module {self.name}={modulename!r} '
+                                  f'does not exist')
             if not isinstance(modobj, self.basecls):
                 raise ConfigError(f'attached module {self.name}={modobj.name!r} '\
                     f'must inherit from {self.basecls.__qualname__!r}')