Switch to Poetry for Packaging and Dependency Management

[mawelborn]

This PR switches to Poetry for packaging and dependency management and Poe for defining and running tasks. I took the opportunity to pay some technical debt and set the stage for future tech debt to be paid more easily. Apologies in advance for the rather large git diff.

• Switched to Poetry for packaging and dependency management.
  • Upgraded indico-client to 6.14.0 for asyncio and Python 3.13 support.
    Updated indico-toolkit to match.
  • indico-client>=6.1.0 requires python>=3.10.
    Updated indico-toolkit to match.
  • indico-client no longer has a hard dependency on numpy, pandas, or msgpack. These have been made optional dependencies in indico-toolkit as well, and are available via extras. indico-client is now the only hard dependency.
    • This reduces the base install size by 75%; container builds are smaller, better, faster, stronger.
• Defined formatting, linting, type checking, and unit testing tasks with Poe.
  • Formatted codebase with ruff (imports) and black (syntax).
  • Fixed codebase issues to pass ruff's E,F,I linting rules.
  • Enabled mypy --strict on existing type-hinted code and future additions.
    • Existing code without valid type hints has been ignored using mypy.ini.
    • Existing code should gradually type hinted as it's worked on in future PRs to ensure type safety.
  • Separated local unit tests and remote integration tests into separate tasks.
    • Local unit tests run by default and execute nearly instantaneously to support fast code -> check -> test feedback loops.
    • Fixed many unit tests and improved fixtures.
    • Remote integration are flaky and have been made a separate task.
    • Executing integration tests has been simplified using pytest arguments.
    • Marked integration tests that are broken on recent IPA versions.
• Fixed GitHub actions workflow, which now executes linting, type checking, and unit testing tasks without errors.
• Updated Readme with a "Not Officially Supported" disclaimer and improved installation and contributing information.
• Updated Changelog.
• Updated repo name to match indico-client-python, indico-client-csharp, indico-toolkit-python, indico-toolkit-csharp naming convention.