Many-to-many fields do not trigger confirmation unless specified in "get_confirmation_fields" method

[e-kondr01]

Describe the bug
I use AdminConfirmMixin and admin.ModelAdmin, setting confirm_change = True. Fields that are not ManyToMany correctly trigger confirmation page. However, my ManyToManyField did not trigger it until I included it in the return value of get_confirmation_fields.

Expected behavior
If no confirmation_fields are specified, then all model fields should trigger confirmation page, even ManyToManyField type ones.

Versions
django-admin-confirm==1.0.0
python 3.11

Additional context
There reason is this line:
https://github.com/TrangPham/django-admin-confirm/blob/main/admin_confirm/admin.py#L58
ManyToManyFields do not appear in model._meta.fields

[TrangPham]

Ah thanks for such a great bug report!

I'd be very happy to review a change from you or others. Marking as a good starter ticket.

[e-kondr01]

A futher note is that after you explicitly specify a M2M field in confirmation_fields, every save will trigger the confirmation page, even if no data has been changed.