Shallow Linux Kernel `git` trees

Why

Full, non-shallow clones of Linux kernel trees are multiple gigabytes in size, and take a lot of time to process.
Shallow clones are much smaller, but cloning/fetching shallow trees impose a huge load on the git server (eg: kernel.org)
kernel.org has git bundles available for download over HTTPS/CDN (simple file download).
- in fact, they recommend their use and have instructions
So this repo does the heavy lifting, grabbing bundles, updating them from live git servers, and makes them shallow and ready for consumption.
- Produced shallow bundles are around 250mb as of 5.18.
- Produced shallow bundles include all tags for the version involved, including -rc tags
- Scheduled runs update the bundles every 24hs, using GitHub actions, including caching.