Sphinx-autobuild

-----------------------

* Add a missing dependency on ``watchfiles``.
* Adopt Ruff in place of flake8 and black.

-----------------------

* Drop ``python-livereload``.
* Add ``starlette`` and ``uvicorn`` as dependencies.
* Implement hot reloading via websockets.
* Run Sphinx rebuilds in an asynchronous executor.

-----------------------

* Declare support for Python 3.9, 3.10, 3.11, and 3.12
* Drop support for Python 3.8 and earlier
* Allow passing relative paths to ``--ignore``
* Support all valid ``sphinx-build`` options (except Make-mode)
* Fix path issues on Windows
* Differentiate pre-build command failures from Sphinx failures

-----------------------

* Change output handling for subprocesses.
* Present helpful error message when the subprocesses fail.
* Skip the main sphinx build, if pre-build commands fail.

-----------------------

* Adopt Calendar Versioning.
* Modernize codebase and require Python 3.6+.
* Directly depend on ``sphinx``.
* Rewritten documentation.
* Invoke sphinx via ``{sys.executable} -m sphinx`` instead of ``sphinx-build``.
* Trim dependencies down to only ``livereload`` and ``sphinx``.
* Drop custom adapter for ``watchdog``.
* Drop ``--poll`` flag.
* Drop single letter variants for flags that were specific to sphinx-autobuild.

------------------

* Remove spurious virtualenv directory from published packages.