[rms_returns]

Not just rust language, to the best of my knowledge, even packagist, the php package manager relies heavily on github for sourcing its packages. But I think they have other resources too, apart from github.

[jdminhbg]

Ruby's bundler doesn't entirely rely on Github, but pulling from a Github repo is a supported option that many take advantage of.

[tatterdemalion]

Rust's package manager doesn't source packages from GitHub (though it will pull packages from a git repo if you ask it to), the source for its index of packages is a git repository on GitHub. https://github.com/rust-lang/crates.io-index