Doesn't work in python 3.10

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'

从 simvue/eco/emissions_monitor.py 开始，在 traceback 中显示的 CO2Monitor 定义处重现 Python 3.10 下的导入失败。检查项目现有的测试或测试设置，以确认支持的 Python 版本。完成的标准是 Python API 能够在 Python 3.10 上正确导入和运行，同时不破坏更新的受支持版本。