Migrate to Poetry v2

• https://python-poetry.org/blog/announcing-poetry-2.0.0/#highlights
• https://python-poetry.org/docs/pyproject/
• https://python-poetry.org/docs/faq/#migrate-pep621-new-static

Todos

• Update pyproject.toml to latest format
  • support include field.
  • Keep classifiers and dependencies dynamic

changed milestone to %1.2.1

added Dev Env label

assigned to @moul

mentioned in issue silkaj#499 (closed)

mentioned in commit 3f6fdf65

mentioned in commit 99e53d76

mentioned in merge request !202 (merged)

closed with merge request !202 (merged)