Fix bug when leaving admin team, setting accepted application as true… (#4090)

* Fix bug when leaving admin team, setting accepted application as true. Fixes #3422

* Addressing PR comments.

crates/api/src/site/leave_admin.rs

@@ -35,6 +35,9 @@ pub async fn leave_admin(
     local_user_view.local_user.id,
     &LocalUserUpdateForm {
       admin: Some(false),
+      // Necessary because admins can bypass the registration applications (if they're turned on)
+      // but then won't be able to log in because they haven't been approved.
+      accepted_application: Some(true),
       ..Default::default()
     },
   )