Release automation revamp

[iskunk]

Ongoing discussion in #343.

This PR replaces the existing "hands-on" release automation for ungoogled-chromium's Debian package with one that is driven by Debian's own chromium package, in a fully automated process (save for rare breakage).

The core of it is the new release.yml file, which covers the entire release cycle. It checks for new chromium source packages in Debian and downloads them (get-latest.sh), converts them into corresponding ungoogled-chromium source packages (convert.sh), and uploads them to OBS for building and distribution (obs-upload.sh). If no new source packages are available, then the superfluous parts of the process are skipped.

There is also a separate script (remote-check.sh) intended to run outside of GitHub, on a home or office PC, that watches for new versions. It is much lighter weight than the GitHub workflow, and allows the release process to be triggered by a Debian package release notification sent by e-mail. (Details of how to set this up may be found in the script's comment header.)

This implementation supports multiple Debian releases simultaneously, at present bookworm (stable) and sid (unstable). It should be expandable to cover other Debian derivatives, provided that a compatible chromium source package is available as a starting point. (Ubuntu is a special case, as no such package is provided officially, but I have a conversion script that can be used to obtain one.)

The workflow requires the following vars/secrets to be defined:

Type	Name	Description
var	DEBFULLNAME	Full name of package maintainer
var	DEBEMAIL	E-mail address of package maintainer
var	OBS_PROJECT	Name of OBS project
var or secret	OSC_USERNAME	OBS account username
secret	OSC_PASSWORD	OBS account password

The dpkg-source-build.patch file is an enhancement that greatly reduces the time (and disk I/O) needed to produce the new Debian source package. It is a modification to dpkg-source(1) that I hope will be eventually merged upstream. More details may be found in the patch's comment header.

You can see a run log of this automation here, and the end products in my personal testing area on OBS.

Please let me know if any aspect of how this works is unclear. This implementation obviously covers a lot of ground, and GitHub's limitations as a CI platform did not help in keeping this simple!

[networkException]

Hi, thanks a lot for continuing the effort. My bandwidth for ungoogled work is sadly mostly limited to releases currently so I haven't had time to look at this (and the amount of bash scares me 😅).

This does look like a really nice approach though and I'll try to squeeze in testing and review in the near future

[iskunk]

Understood that time is tight. Looking forward to hearing your thoughts when you have the opportunity.

There's a lot of moving parts, to be sure! I try to aim for well-commented / self-documenting code, so if any part of it doesn't come across clearly, let me know and I'll polish it up some more.

[iskunk]

I've updated the cache expiration logic to avoid a corner case where an orig-source tarball may be deleted prematurely.

And I also added the remote-check.sh script, which I had forgotten to include in my original push :-]