Update poetry to 2.2.1

[ArBridgeman]

Summary

In some of our pipelines, it has been noted that poetry < 2.2.1 is occasionally leading to issues with the wrong Python version being used. We want to prevent this by upgrading to poetry "2.2.1".

Preparing for the Task

These are not required, but these steps might prove useful:

• The PTB includes pre-commit hooks, which can be installed as described here:
  https://exasol.github.io/python-toolbox/main/user_guide/features/git_hooks/index.html#configuration
• Documentation on the action might be useful:
  https://exasol.github.io/python-toolbox/main/github_actions/python_environment.html

Task(s)

Code Changes

• In the PTB's pyproject.toml, update requires-poetry to ">=2.2.1"
• In the terminal, run poetry check; resolve any errors and consider if useful to update warnings (best effort).
• In the project-template/{{cookiecutter.repo_name}}/pyproject.toml), update requires-poetry to ">=2.2.1"
• In .github/actions/python-environment/action.yml, update default (under poetry-version) to "2.2.1"
• Check if we should update .github/actions/python-environment/ext/get_poetry.py (which comes from poetry)
  -> Note that @tomuben added and instructions for the developer guide are missing (per Describe how to update get_poetry.py #558 )
• See that that Pull Request template tasks (see any recent PR for an example) are complete for this one. Feel free to ask questions if unclear.

Documentation Changes

• In the unreleased.md, add an entry for the fix for this issue (see other entries).
• Please add a summary in the unreleased.md, detailing what another project would need to do to use this newer version
  -> update requires-poetry in pyproject.toml and execute poetry check to verify it's alright.
  -> doc/changes/changes_1.0.0.md is a similar situation
• Update doc/github_actions/python_environment.rst with new poetry-version

After work is approved

• Coordinate with other PTB maintainers about creating a major release - there might be important work we cannot split
• Create a tracking task for the team to track which repositories have been updated or still need to
• Announce the tracking task in a common team channel