Document issues with using builtin `git` on CUBIC when also using mamba/conda/micromamba/miniforge environments

[tsalo]

We've been getting the following kind of error when trying to use git on CUBIC:

Cloning into 'nibs'...
fatal: unable to access 'https://github.com/PennLINC/nibs.git/': error setting certificate verify locations:
 CAfile: /etc/ssl/certs/ca-certificates.crt
 CApath: none`

The solution we've come up with so far is to install git in an environment and use that instead of the module version added by the CUBIC admins. The CUBIC admins do not seem to like mamba etc. since these tool mess with system settings in the user's profile, which means that we are effectively on our own to find a sustainable workaround.

[tsalo]

@mattcieslak was able to resolve the issue by installing ca-certificates in his environment. We should try testing this in a minimal environment to make sure it's the only thing we need to do to fix the problem.