Pymatsolver

What's Changed
* Accepts Linear Operator as a valid input for solvers by jcapriot in https://github.com/simpeg/pymatsolver/pull/51


**Full Changelog**: https://github.com/simpeg/pymatsolver/compare/v0.3.0...v0.3.1

What's Changed
* test on python 3.10 by lheagy in https://github.com/simpeg/pymatsolver/pull/37
* cleanup tests by jcapriot in https://github.com/simpeg/pymatsolver/pull/38
* Typo in documentation by rowanc1 in https://github.com/simpeg/pymatsolver/pull/40
* Remove Travis badge from README.rst by lheagy in https://github.com/simpeg/pymatsolver/pull/44
* Fix CI by mplough-kobold in https://github.com/simpeg/pymatsolver/pull/46
* Add mumps solver by jcapriot in https://github.com/simpeg/pymatsolver/pull/43
* Remove nosetest and convert tests to pytest by mplough-kobold in https://github.com/simpeg/pymatsolver/pull/47
* Refactor base class by jcapriot in https://github.com/simpeg/pymatsolver/pull/48
* Switch to pyproject.toml based install by jcapriot in https://github.com/simpeg/pymatsolver/pull/49
* Add conjugate solve by jcapriot in https://github.com/simpeg/pymatsolver/pull/50

New Contributors
* mplough-kobold made their first contribution in https://github.com/simpeg/pymatsolver/pull/46

**Full Changelog**: https://github.com/simpeg/pymatsolver/compare/v0.2.0...v0.3.0

This should work better when mkl is not available.

The version that was pushed to PyPI was incorrect, causing problems in the pip install. This has now been fixed.

I have brought back mumps and also updated the library substantially. Organized into more reasonable folders and improved the `setup.py` experience.

- Removed mumps (https://github.com/rowanc1/pymatsolver-mumps)
- Shortened names of Solvers
- Added splu, cg and sp from scipy solvers