store_timeseries fails if version datetime has unspecified timezone

[msweier]

If a timeseries version is not a datetime object that has a specified timezone, the store will fail because there is no "Z" at the end.

May want to consider putting a check in the timeseries_df_to_json function that checks if the datetime object has a timezone specified and throw an error or assume UTC.

https://github.com/HydrologicEngineeringCenter/cwms-python/blob/509ae4050d592631942c03e564dd85e8bd22810b/cwms/timeseries/timeseries.py#L250C1-L253C32