Xocto

Includes:

- Remove the assert_never helper ([16](https://github.com/octoenergy/xocto/pull/16))
- Add common pact testing test fixtures 18 ([18](https://github.com/octoenergy/xocto/pull/18))
- Add S3 reusable code ([19](https://github.com/octoenergy/xocto/pull/19))

Starting from this release, this project will be versioned using [Semantic Versioning ](https://semver.org/):

> Given a version number MAJOR.MINOR.PATCH, increment the:
>
> - MAJOR version when you make incompatible API changes
> - MINOR version when you add functionality in a backwards compatible manner
> - PATCH version when you make backwards compatible bug fixes
> - Additional labels for pre-release and build metadata are available as extensions to the MAJOR.MINOR.PATCH format.

In practice this has been happening already, but we are now making it official.

This is an unknown release, mentioned here for the sake of completeness.

Includes:

- The localtime functions now return a Python datetime timezone UTC instead of a pytz UTC

Includes:

- Fix `is_local_time()` when using Python's datetime timezone UTC

Includes:

- Support for Django v4 (currently only supports `USE_DEPRECATED_PYTZ = True`)

Includes:

- Add the localtime, ranges, numbers and types modules
- Update black and isort