Chronumental

What's Changed
* Remove variance branch length parameter by theosanderson in https://github.com/theosanderson/chronumental/pull/26
* format and remove old unused eval by theosanderson in https://github.com/theosanderson/chronumental/pull/27


**Full Changelog**: https://github.com/theosanderson/chronumental/compare/v0.0.54...v0.0.55

Fixes an issue related to a breaking change in latest numpy ver

What's Changed
* Update input_mod.py by theosanderson in https://github.com/theosanderson/chronumental/pull/22


**Full Changelog**: https://github.com/theosanderson/chronumental/compare/v0.0.53...v0.0.54

Fixes the use of GPU

Clarifies branch_len gth_ ariance parameter, and relaxes this prior