Conda install option

[michaelcdevin]

/cc @cmichelenstrofer @ryancoe

We are using pygmsh as part of a pseudo-spectral code for control co-design of wave energy converters. We are in the process of packaging our code into a conda build and uploading to conda-forge to simplify installation for users due to other package dependencies when installing via pip. However, since pygmsh is only pip-installable, we will have to ask users to pip install pygmsh as a separate step. Since gmsh is already available on conda-forge, it would be great if pygmsh could be added as well.

We are very interested in continuing to use this package and are willing to help set this up if needed.