3.4.3: Maintenance release

[Guyer, Jonathan E. Dr. (Fed)]

This maintenance release adds a new example contributed by @Jon83Carvalho, clarifies many points in the documentation, migrates all CI to Azure, updates to using wheels for distribution, and substantially refactors matrices to work more consistently across solvers.

Please see https://github.com/usnistgov/fipy/discussions/873 for more information.