licenses, urls and pixi

[baszalmstra]

This PR adds:

• A pixi.toml to make working with vinca easier.
• Parsing of licenses and including those in the about section
• Parsing urls and adding those to the about section
• Parsing of the description and adding it to the about.summary.
• Fixes a number of flake8 issues.

As an example the following is generated for rosunit:

about:
  homepage: http://wiki.ros.org/rosunit
  repository: https://github.com/ros/ros
  license: BSD-3-Clause
  summary: Unit-testing package for ROS. This is a lower-level library for rostest and handles unit tests, whereas rostest handles integration tests.

Fixes #54

[Tobias-Fischer]

Amazing, thanks so much for this!!

[traversaro]

Thanks a lot @baszalmstra !