We have kept support for Python 3.9 beyond its recommended life span although it was dropped by the scientific community in April 2024 (https://numpy.org/neps/nep-0029-deprecation_policy.html).
Initially, a critical vulnerability in Dask <= 2024.8.2 forced us to start droping Python 3.9 as Dask dropped support for Python 3.9 in version 2024.8.1, but this vulnerability disappeared so it is less urgent now. We can wait until a new issue arises.

After this change we will still have at least 3 working versions of Python (3.10-12).

Subtasks:

Remove python 3.9 in automatic tests (.github/workflows/starfish-prod-ci.yml)
Update 4 requirements files
Bump python version to 3.10 in docker/Dockerfile
Update docs (README.rst & docs/source/installation/index.rst)
Update comments in examples/quick_start/plot_quick_start.py
Remove Python 3.9 in packaging files (pyproject.toml)
Make new release