Decaylanguage

* Universal representation of decay chains:
- Test suite extended for a significantly better test coverage.
* CI and tests:
- Run doctests via pytest.
- Updates to pre-commit hooks and CI YAML files.

* Dependencies:
- Package dependent on ``Particle`` version 0.21.x.
- Adapted to Python 3 only Lark 1.x series.
- Support for Python 3.11 added and support for Python 3.6 removed.
* Parsing of decay files (aka .dec files):
- Updated to the latest Belle II master file DECAY.DEC.
- Added support for ModelAlias keyword used in Belle II decay files.
* Miscellaneous:
- Added a CITATION.cff file.
- Moved over to using hatchling.
- Started using AllContributors to acknowledge contributions explicitly.
* CI and tests:
- Updates to pre-commit hooks and CI YAML files.
- Various improvements to the CI.

* Parsing of decay files (aka .dec files):
- Minor improvements such as in type checking.
- Documentation updates.
- More tests.
* CI and tests:
- Several improvements to GHAs.
- Various hooks version updates.
- Added a `dependabot.yml`.

* Universal representation of decay chains:
- Extra documentation and examples of usage.
- Test suite extended.
* Miscellaneous:
- Type checking introduced.
* Tests:
- CI now tests the notebooks as well.
- Various hooks version updates.

Package dependent on Python 3 only ``Particle`` version 0.20.
Otherwise identical to series 0.13.

* Universal representation of decay chains:
- Adapt DOT representations to work with graphviz >= 0.19, which broke the API removing `_repr_svg_()`.
* Tests:
- Various hooks version updates.