document how to install git-hosted python packages

[zeke]

This PR adds some documention for people who are using git-based Python dependencies. This used to work, but we switched to using a slimmer image that doesn't include git in #1214

Resolves #1381

[technillogue]

I don't think this is necessary in latest versions of cog, it was fixed in #1233 and released in https://github.com/replicate/cog/releases/tag/v0.9.0-beta1

[yondonfu]

@technillogue

I don't think this is necessary in latest versions of cog

FYI I'm on cog v0.9.0-beta11 and I seem to still be running into the issue described in #1381. In my case, I have a git clone command under the run key in my cog.yaml and cog build fails when it reaches that line complaining that git could not be found. I added git under system_packages to fix the issue.

See cog --version output below:

cog version 0.9.0-beta11 (built 2023-11-28T17:38:26Z)

[zeke]

Thanks for the heads-up, @yondonfu. Maybe we should just land this documentation as it does apply to some versions of Cog that are out there in the wild, apparently including the latest versions.