lightGBM upgrade

[robmarkcole]

Document experience upgrading to lightgbm==4.1.0 which is required for Mac wheels

• Get ModuleNotFoundError: No module named 'sklearn' - add to requirements
• AttributeError: module 'hashlib' has no attribute 'scrypt' - strange as this appears to be an error in python < 3.6. Full error below:

 > iris demo
Welcome to IRIS! No admin user was detected so please enter a new admin password.
python version: 3.9.6 (default, Oct  1 2023, 17:38:10) 
[Clang 15.0.0 (clang-1500.0.40.1)]
New admin password: 
Retype admin password: 
Traceback (most recent call last):
  File "/Users/robin.cole/Documents/GitHub/iris/venv/bin/iris", line 33, in <module>
    sys.exit(load_entry_point('iris', 'console_scripts', 'iris')())
  File "/Users/robin.cole/Documents/GitHub/iris/iris/__init__.py", line 54, in run_app
    create_default_admin(app)
  File "/Users/robin.cole/Documents/GitHub/iris/iris/__init__.py", line 106, in create_default_admin
    admin.set_password(password)
  File "/Users/robin.cole/Documents/GitHub/iris/iris/models.py", line 46, in set_password
    self.password_hash = generate_password_hash(password)
  File "/Users/robin.cole/Documents/GitHub/iris/venv/lib/python3.9/site-packages/werkzeug/security.py", line 101, in generate_password_hash
    h, actual_method = _hash_internal(method, salt, password)
  File "/Users/robin.cole/Documents/GitHub/iris/venv/lib/python3.9/site-packages/werkzeug/security.py", line 43, in _hash_internal
    hashlib.scrypt(password, salt=salt, n=n, r=r, p=p, maxmem=maxmem).hex(),
AttributeError: module 'hashlib' has no attribute 'scrypt'