Pyee

Compatibility:

- Drop 3.6 support

New features:

- New `EventEmitter.event_names()` method (see PR 96)
- Type annotations and type checking with `pyright`
- Exprimental `pyee.cls` module exposing an `evented` class decorator
and a `on` method decorator (see PR 84)

Moved/deprecated interfaces:

- `pyee.TwistedEventEmitter` -> `pyee.twisted.TwistedEventEmitter`
- `pyee.AsyncIOEventEmitter` -> `pyee.asyncio.AsyncIOEventEmitter`
- `pyee.ExecutorEventEmitter` -> `pyee.executor.ExecutorEventEmitter`
- `pyee.TrioEventEmitter` -> `pyee.trio.TrioEventEmitter`

Removed interfaces:

- `pyee.CompatEventEmitter`

Documentation fixes:

- Add docstring to `BaseEventEmitter`
- Update docstrings to reference `EventEmitter` instead of `BaseEventEmitter`
throughout

Developer Setup & CI:

- Migrated builds from Travis to GitHub Actions
- Refactor developer setup to use a local virtualenv

- Correct version in docs

- Add .readthedocs.yaml file
- Remove vcversioner dependency from docs build

- Remove test_requires and setup_requires directives from setup.py (closing 82)
- Remove vcversioner from dependencies
- Streamline requirements.txt and environment.yml files
- Update and extend CONTRIBUTING.rst
- CI with GitHub Actions instead of Travis (closing 56)
- Format all code with black
- Switch default branch to `main`
- Add the CHANGELOG to Sphinx docs (closing 51)
- Updated copyright information

- Improve thread safety in base EventEmitter
- Documentation fix in ExecutorEventEmitter

- Update README to reflect new API