document this better: End of life for the free tier of the Magic Nix Cache

[brianmay]

Most people don't read their logs unless it fails and wont notice the pending shutdown of this action.

Yes, I know this is tricky.

But there are places you could document this, but haven't. For example, the github website. https://github.com/DeterminateSystems/magic-nix-cache-action

At the very least, please add a link from the github page to the blog post.

https://determinate.systems/posts/magic-nix-cache-free-tier-eol/

Thanks

[otavio]

At the same time, their justification to not work anymore on this was the lack of the protobuf specification. However, the community has already produced the protobuf definitions and this should allow the work to continue.

[brianmay]

Is it no longer the case that this is deprecated? #134 #135.

Not sure, as I am seeing errors trying to use this as per instructions.

2025-08-13T02:09:13.744364Z ERROR magic_nix_cache: FlakeHub: cache initialized failed: Unauthenticated: Cannot find netrc credentials for https://api.flakehub.com/
at magic-nix-cache/src/main.rs:398