Strenum

What's Changed
* Add stub files for type hints. by irgeek in https://github.com/irgeek/StrEnum/pull/19
* Fix HttpHeaderCaseStrEnum docstring by ericbn in https://github.com/irgeek/StrEnum/pull/20
* Make it clearer that Http-Header-Case uses title by ericbn in https://github.com/irgeek/StrEnum/pull/21
* Update README.md by ericbn in https://github.com/irgeek/StrEnum/pull/22

**Full Changelog**: https://github.com/irgeek/StrEnum/compare/v0.4.9...v0.4.10

Pytest no longer supports Python 3.6 so it's getting very difficult to maintain tests for that version. Python 3.6 went EOL about 12 months ago so there isn't much value in continuing to support it.

There are no code changes in this release, just some updates to the GH Actions config and PyPI classifiers.

This release makes some improvements to the README and adds some missing tests. The functionality of the package hasn't changed, though.

Name conversion for `auto()` values

This release adds several new subclasses that mangle the enum member name to produce the `auto()` value. Supported conversions:

* camelCase
* PascalCase
* kebab-case
* snake_case