Trigger automated build of new debian packages when new tor version is released

Currently our procedure for creating a new debian package happens with a very manual procedure documented in TPA's wiki and only in response to an issue from the devs creating the release.

This is slow and error-prone.

In #42331 (comment 3271843) we've briefly discussed the possibility of getting this more automated.

The idea would be for the Network Team's CI to somehow trigger some action on TPA's side that would create the new debian package.

One gotcha that we'll have to look into is that currently the new debian packages have a pgp-signed signature from one of the allowed uploaders. This lets TPA's CI send the package automatically to reprepro. We can't have CI create that signature in the current state of things.

/cc @dgoulet