calendar-button: change widget to standalone list for sidebar

The sync entry is dropped here in favour of one in the
main menu.

Signed-off-by: Markus Göllnitz <camelcasenick@bewares.it>
Part-of: <https://gitlab.gnome.org/GNOME/gnome-calendar/-/merge_requests/542>

src/gui/meson.build

@@ -16,7 +16,7 @@ built_sources += gnome.compile_resources(
 
 sources += files(
   'gcal-application.c',
-  'gcal-calendar-button.c',
+  'gcal-calendar-list.c',
   'gcal-drop-overlay.c',
   'gcal-event-popover.c',
   'gcal-event-widget.c',