Make copyright year in Flower docs dynamic

[Robert-Steiner]

Issue

The copyright year is currently hardcoded. This PR adds a bit of python code to make it dynamic.

Description

Related issues/PRs

Proposal

Explanation

Checklist

• Implement proposed change
• Write tests
• Update documentation
• Update changelog
• Make CI checks pass
• Ping maintainers on Slack (channel #contributions)

Any other comments?

[tanertopal]

@Robert-Steiner can you modify the other conf.py and also add a test that checks all sphinx conf.py files for that code so that it's ensured that in the future we always use that dynamic copyright year?

[Robert-Steiner]

@Robert-Steiner can you modify the other conf.py and also add a test that checks all sphinx conf.py files for that code so that it's ensured that in the future we always use that dynamic copyright year?

I have modified the other conf.py files and added a test in the CI. Let me know what you think. I used the ::error annotation to let the errors appear in the summary. here is an example https://github.com/adap/flower/actions/runs/7143334049