[Python] Workaround for plotting on remote server.

[ReinderVosDeWael]

Many users have reported issues with using plot_hemispheres on a remote server. This issue stems from vtk, one of our dependencies, requiring a display to exist. If you are running into this issue, you may want to try this experimental workaround. If you do, please let us know whether this worked for you.

The workaround is as follows. First, install conda. Once installed, run the following:

conda config --add channels conda-forge
conda install mesalib --channel conda-forge --override-channels --freeze-installed
conda install vtk --channel conda-forge --override-channels --freeze-installed
# if conda tries to install a build of vtk that does not start with osmesa_* force this build using the following:
# Note that the exact vtk version and build may have to be adjusted in the future.
# conda install vtk==9.1.0=osmesa_py39h8ab48e2_107 --channel conda-forge --override-channels --freeze-installed