net-mgmt/netbox: Update to 4.2.8

Changelog:

Enhancements:
* Introduce the --readonly flag on upgrade script
* Add trace buttons to terminations under cable view
* Enable filtering prefixes by group of assigned VLAN
* Include FHRP group name on interface lists
* Add 802.1Q mode to interface filter form
* Show count of related VLAN groups under cluster view
* Add "copy to clipboard" button for rendered config
* Enable filtering devices by location slug
* Add filtering by VLAN translation policy to interface
  filter forms

Bug Fixes:
* prepare_cloned_fields() should validate cloning support on model
* Ensure default custom field values are respected when creating
  objects via the REST API
* Include missing related object counts under certain views
* Omit "clear" button on required choice fields
* Preserve ordering of terminations in cable traces
* Virtual chassis form should exclude members of other VCs when
  adding members
* Fix custom field choices bulk import support for base_choices
* The load_yaml() convenience method on BaseScript should use
  SafeLoader
* Language cookie should respect SESSION_COOKIE_SECURE value
* Allow label reuse when creating multiple components from a pattern
* Restore editing conflict protection for several object forms

https://github.com/netbox-community/netbox/releases/tag/v4.2.8

MFH:		2025Q2
(cherry picked from commit 3a7416ab)