Add git-filter-repo to packages

What does this merge request do and why?

Gitaly recently added a new RPC that uses git-filter-repo to modify repository history. Add it to our list of dependencies.

On Ubuntu, the filter-repo was only introduced with 22.04, so we fall back to installing it via pip.

How to set up and validate locally

Run gdk update, validate that the git-filter-repo package is now installed on your host.

Impacted categories

The following categories relate to this merge request:

• gdk-reliability - e.g. When a GDK action fails to complete.
• gdk-usability - e.g. Improvements or suggestions around how the GDK functions.
• gdk-performance - e.g. When a GDK action is slow or times out.

Merge request checklist

• This change is backward compatible. If not, please include steps to communicate to our users.
• [-] Tests added for new functionality. If not, please raise an issue to follow-up.
• [-] Documentation added/updated, if needed.
• [-] Announcement added, if change is notable.
• [-] gdk doctor test added, if needed.
• [-] Add the ~highlight label if this MR should be included in the CHANGELOG.md.