Req2flatpak

Highlight: Compatibility with Python 3.12

Improvements for Development:
* Improved CI 73 79 82
* Added devcontainers configuration 65
* Now using ruff for linting 87

Fixes:
* Fixed an error when no urls are found in a pypi release in 71

Maintenance and dependency updates:
* Updated dependencies in 62 74
* Improved docs in 77 81 86
* Now using `packaging` instead of the deprecated `pkg_resources` package 76

**Full Changelog**: https://github.com/johannesjh/req2flatpak/compare/v0.2...v0.3

Highlight: req2flatpak can now generate yaml output.

Features:

- Adds yaml output.
It is now possible to generate yaml output by specifying a ``.yaml`` file extension
or by specifying the ``--yaml`` commandline option.

Bugfixes:

- Fixes sorting when architecture is None - `34 <https://github.com/johannesjh/req2flatpak/pull/34>`_
- Fixes exception handling with invalid platforms - `39 <https://github.com/johannesjh/req2flatpak/pull/39>`_