Buf v0.13.0 is released - use git binary for internal git clones

[bufbuild-announce]

We have released Buf v0.13.0.

This changes Buf from using a Golang library for git clones, to using the git binary itself. This change results in much more stable git repository clones, and also matches what other tools do.

This also has the effect of allowing usage of your system git credential management for private repository clones using https or ssh.

Remote tarballs and image files can now also use your netrc file for authentication.

The brew tap has been updated, and the authentication documentation has also been updated to reflect the above changes. Let us know if this helps your usage!