Doesn't work in python 3.10

[wk9874]

Description of Bug

Python API crashes on python 3.10, since it uses timezone.UTC, which is an alias that was only introduced in 3.11.

Steps To Reproduce

Steps to reproduce the behavior:

1. Try running it on 3.10

Expected behavior

Runs correctly

Actual Behaviour

    from simvue.config.user import SimvueConfiguration
../../../Library/Caches/pypoetry/virtualenvs/simvue-moose-SyxDCI6N-py3.10/lib/python3.10/site-packages/simvue/config/user.py:39: in <module>
    from simvue.eco.config import EcoConfig
../../../Library/Caches/pypoetry/virtualenvs/simvue-moose-SyxDCI6N-py3.10/lib/python3.10/site-packages/simvue/eco/__init__.py:11: in <module>
    from .emissions_monitor import CO2Monitor as CO2Monitor
../../../Library/Caches/pypoetry/virtualenvs/simvue-moose-SyxDCI6N-py3.10/lib/python3.10/site-packages/simvue/eco/emissions_monitor.py:41: in <module>
    class CO2Monitor(pydantic.BaseModel):
../../../Library/Caches/pypoetry/virtualenvs/simvue-moose-SyxDCI6N-py3.10/lib/python3.10/site-packages/simvue/eco/emissions_monitor.py:82: in CO2Monitor
    _last_local_write = pydantic.PrivateAttr(datetime.datetime.now(tz=datetime.UTC))
E   AttributeError: module 'datetime' has no attribute 'UTC'