Upgrade to python 3.10

[David548219]

Is your feature request related to a problem? Please describe.
Modern python packages require python versions >=3.10. This is a problem when trying to use alerta plugins which require them.

Describe the solution you'd like
Upgrade python base image to a newer one, for example 3.10

Additional context
Python 3.9 reached end of life in October 2025. It is currently used as a base image