Update requirements.txt for refreshing JSON templates via a git fetch

The following code allows for templates to be refreshed by a NICOS script, which will be useful for instruments and so on with minimum interference:

from git import Repo

try:
    from general_inst import get_nicos_inst as gnl
except ImportError:
    import re

    class Gnl:
        """In case we cannot import nicos-scripts"""

        def __init__(self):
            pass

        def get_nicos_inst(self):
            """Method to fetch name from nicos.conf"""
            with open("nicos.conf", encoding="utf-8") as f:
                for line in f:
                    r = re.search(r'^instrument = "(.*)"', line)
                    if r is not None:
                        return r.group(1)

            return "NONE"

    gnl = Gnl()


repo = Repo("nexus-json-templates")

while True:
    for inst, struct, sample in instruments:
        repo.remotes.origin.fetch()
        diff = repo.git.diff("origin/main", name_only=True)
        if inst in diff:
            repo.git.pull()
            printwarning(
                f"Updated JSON files: {diff}, on NICOS instance: {gnl.get_nicos_inst()}"
            )

But for this to work the git module in python needs to be available from deployment.