python : add check-requirements.sh and GitHub workflow (#4585)

* python: add check-requirements.sh and GitHub workflow

This script and workflow forces package versions to remain compatible
across all convert*.py scripts, while allowing secondary convert scripts
to import dependencies not wanted in convert.py.

* Move requirements into ./requirements

* Fail on "==" being used for package requirements (but can be suppressed)

* Enforce "compatible release" syntax instead of ==

* Update workflow

* Add upper version bound for transformers and protobuf

* improve check-requirements.sh

* small syntax change

* don't remove venvs if nocleanup is passed

* See if this fixes docker workflow

* Move check-requirements.sh into ./scripts/

---------

Co-authored-by: Jared Van Bortel <jared@nomic.ai>

convert-persimmon-to-gguf.py

@@ -1,3 +1,4 @@
+#!/usr/bin/env python3
 import torch
 import os
 from pprint import pprint