License update

• clean LGPL-3 license following GNU recommendations in COPYING and COPYING.LESSER
• all authors with their roles mentioned in AUTHORS.md file
• added LICENSE section in readme
• added LICENSE.md file with UFZ copyright notice
• COPYING, COPYING.LESSER, LICENSE.md and AUTHORS.md automatically detected by hatch and added to sdist and wheels

docs/source/about/authors.rst

-.. include:: ../../CHANGELOG.md
+.. include:: ../../../AUTHORS.md
    :parser: myst_parser.sphinx_