Mediatimestamp

What's Changed
* Regenerate static files by j616 in https://github.com/bbc/rd-apmm-python-lib-mediatimestamp/pull/81
* Add commit check workflow by j616 in https://github.com/bbc/rd-apmm-python-lib-mediatimestamp/pull/82
* Regenerate static files by GeorginaShippey in https://github.com/bbc/rd-apmm-python-lib-mediatimestamp/pull/83
* Regenerate static files by j616 in https://github.com/bbc/rd-apmm-python-lib-mediatimestamp/pull/84
* Regenerate static files by philipnbbc in https://github.com/bbc/rd-apmm-python-lib-mediatimestamp/pull/85
* Add to_float timestamp methods and further support to negative timestamps by philipnbbc in https://github.com/bbc/rd-apmm-python-lib-mediatimestamp/pull/86

New Contributors
* GeorginaShippey made their first contribution in https://github.com/bbc/rd-apmm-python-lib-mediatimestamp/pull/83

**Full Changelog**: https://github.com/bbc/rd-apmm-python-lib-mediatimestamp/compare/4.0.1...5.0.0

What's Changed
* Regenerate static files by samdbmg in https://github.com/bbc/rd-apmm-python-lib-mediatimestamp/pull/74
* Add support for GHA by AndrewGibb in https://github.com/bbc/rd-apmm-python-lib-mediatimestamp/pull/75
* Regenerate static files by j616 in https://github.com/bbc/rd-apmm-python-lib-mediatimestamp/pull/77
* Update static files by AndrewGibb in https://github.com/bbc/rd-apmm-python-lib-mediatimestamp/pull/76
* Regenerate static files by AndrewGibb in https://github.com/bbc/rd-apmm-python-lib-mediatimestamp/pull/78
* Remove Jenkins files and update README.md by AndrewGibb in https://github.com/bbc/rd-apmm-python-lib-mediatimestamp/pull/79
* Regenerate static files by j616 in https://github.com/bbc/rd-apmm-python-lib-mediatimestamp/pull/80


**Full Changelog**: https://github.com/bbc/rd-apmm-python-lib-mediatimestamp/compare/4.0.0...4.0.1

All python 2.7 support will be dropped after this version, except for essential bugfixes.

If you need future features please use Python 3.

- Dropped all support for python 2.7
- Swapped the mutable and immutable defaults
- Removed the inclusion of the constants at the top level
- Removed all mutable timestamps

Added extend_to_encompass_timerange function for immutable.TimeRange.
Hardcode use of python3.4 in RPM spec file to workaround missing python3 soft link in recent (>3.4.9) centos python34 RPM.

Removed the PRESERVE_START and PRESERVE_END rounding options which are used in TimeRange.normalise().