What's Changed
`sigtools` 4.0 drops Python 2 support and adds support for PEP-563 annotations.
* Remove py2 from CI and deps by epsy in https://github.com/epsy/sigtools/pull/24
* Drop Python2 compatibility, update copyright notices by epsy in https://github.com/epsy/sigtools/pull/25
* add shared CI workflow by epsy in https://github.com/epsy/sigtools/pull/27
* Use shared CD by epsy in https://github.com/epsy/sigtools/pull/29
* Trim down tox.ini by epsy in https://github.com/epsy/sigtools/pull/31
* Update sigtools.support.f to use native Python syntax by default by epsy in https://github.com/epsy/sigtools/pull/30
* Use setuptools_scm for version by epsy in https://github.com/epsy/sigtools/pull/32
* Fix missing secret requirement in CD workflow by epsy in https://github.com/epsy/sigtools/pull/33
* Allow specifying future compilation features in sigtools.support by epsy in https://github.com/epsy/sigtools/pull/34
* parameters are now upgraded with information to support postponed annotations by epsy in https://github.com/epsy/sigtools/pull/35
* run test_autoforwards both with and without pep563 annotations by epsy in https://github.com/epsy/sigtools/pull/36
* Update documentation, revisit Upgraded* interfaces by epsy in https://github.com/epsy/sigtools/pull/37
* put "how to use forwards" in the "reference" section by epsy in https://github.com/epsy/sigtools/pull/38
* list features in docs index by epsy in https://github.com/epsy/sigtools/pull/39
* Update sigtools.sphinxext to avoid deprecated no_docstring API by epsy in https://github.com/epsy/sigtools/pull/40
* Fix incorrect version in pending deprecation by epsy in https://github.com/epsy/sigtools/pull/41
* add a test for sphinxext + autoforwards by epsy in https://github.com/epsy/sigtools/pull/43
* update copyright for 2022 by epsy in https://github.com/epsy/sigtools/pull/42
**Full Changelog**: https://github.com/epsy/sigtools/compare/2.0.3...v4.0.0