Update the checked_oint & mazeppa checksums

[hirrolot]

The following happened:

1. I've rebased the master branch with git-filter-repo only to change commit metadata.
2. GitHub re-created release archive files with slightly different compressed byte content but same content after decompression.
3. Therefore, the MD5 and SHA-512 hashes of the source code archives became different.

Interestingly, GitHub doesn't even guarantee stability of source code archives, so this situation could have happened without a forceful push. Nonetheless, the easiest solution would be to just update the checksums according to md5sum and sha512sum for respective archives.

Needed for #26943.

[hannesm]

FWIW, for the future, topkg-care pioneered an approach to generate a reproducible tarball on release time which dune-release picked up. And GitHub allows you to upload a custom tarball on release time. So if you use e.g. dune-release for your releases you won't end up relying on GitHub.

For the present PR, I'm not a fan of changing the checksums, but instead finding the tarballs in one of the caches and uploading them somewhere. I'm not sure what the opam-repository policy in this respect is at the moment.

[hirrolot]

finding the tarballs in one of the caches and uploading them somewhere

Where should I locate them? I couldn't find any information about where GitHub stores previously generated source code tarballs, and I don't have them locally.

[shonfeder]

Where should I locate them? I couldn't find any information about where GitHub stores previously generated source code tarballs, and I don't have them locally.

Try having a look at the archives at https://github.com/ocaml/opam-repository/wiki/FAQ#how-to-find-lost-archives-of-packages . LMK if you need any support in hunting them down!