Publish the .proto files for the new cache service

[grahamc]

Hi,

My company has a project, Magic Nix Cache, that uses the GitHub Actions cache API to serve as a Nix binary cache in CI.

Given the new cache backend and the sunsetting of the old one, I'm looking to update a project that uses the v1 api directly. It looks like the .proto files are not checked in to this repo, and only the generated code is present.

Are these proto files intentionally excluded? If so, Magic Nix Cache is going to break suddenly and be very challenging to make work again. That would be unfortunate, because it gives Nix users a no/low-cost binary cache for small projects' CI, using just the GitHub Actions primitives.

Please consider publishing the proto files.