Pyxdsm

What's Changed
* Switch to GHA by nwu63 in https://github.com/mdolab/pyXDSM/pull/47
* added GHA badge by marcomangano in https://github.com/mdolab/pyXDSM/pull/49
* Add auto fading for off-diagonal blocks by nwu63 in https://github.com/mdolab/pyXDSM/pull/50
* Change logic for auto-fading connections by A-CGray in https://github.com/mdolab/pyXDSM/pull/53


**Full Changelog**: https://github.com/mdolab/pyXDSM/compare/v2.2.2...v2.3.0

What's Changed
* Update azure-pipelines.yaml by marcomangano in https://github.com/mdolab/pyXDSM/pull/43
* Add ability to specify additional latex packages by A-CGray in https://github.com/mdolab/pyXDSM/pull/44
* Allow fading of connection edges, inputs, and outputs by A-CGray in https://github.com/mdolab/pyXDSM/pull/45

New Contributors
* A-CGray made their first contribution in https://github.com/mdolab/pyXDSM/pull/44

**Full Changelog**: https://github.com/mdolab/pyXDSM/compare/v2.2.1...v2.2.2

New features
- Add option to write/build files in a specified directory (40)
Bugfixes
None
Maintenance
- defined constants for LEFT and RIGHT (42)
- Azure Transition (38)

This minor release drops support for Python 2.x. We currently test 3.6, 3.7, and 3.8. Other changes include:
- Documentation update (34, 35)
- Updated tests and changed `os.system` call (37)

This is another patch release for pyXDSM:
- defined constants for the names of the different components, which can now be imported (31)
- maintenance updates (32)

This is a bugfix release:
- Bug fix for stacked systems (29)
- Better error checking for `connect` function (28)