Add github commit hash to replica log

Created by: scarlehoff

I think it might make sense to add to the beginning to the chi2 log of the replica, some information about the "version" of the repository that the code is running.

Possible use-case, I have 100 replicas running in the background in the cluster. I do a conda update somewhere in the middle of them running, now I have say 50 that have run with a different version of the repository, potentially changing results. This would allow me to know if that was indeed the case.

Or there is some fit in the server that we cannot reproduce, this would allow us to know exactly with what commit it was done.

What do people think?