chore: Remove `ChangeMilestoneStatus` (#6741)
- Introduced in 5ed5aa5228feba935679df8cb676af62018cc25d and removed in
4027c5dd7c11c1256094e202be591ec1b86a011e.
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/6741
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Co-authored-by: Gusted <postmaster@gusted.xyz>
Co-committed-by: Gusted <postmaster@gusted.xyz>
authored by