The `ANIM_animdata_update` wasn't handling the GPv3 cases.
This meant that e.g. changing the selection of keyframes did not
cause an update to be triggered.
This fixes the issue by making sure we call `ANIM_list_elem_update`
for all the grease pencil channel types.
Pull Request: https://projects.blender.org/blender/blender/pulls/122167
f011d8f508