Include RMM v0.10 in parflow-dependencies?

[reedmaxwell]

@smithsg84 @hokkanen it seems like we should include the correct version of RMM to run w/ the CUDA backend here. This would be helpful as RMM is getting increasingly difficult to install.

[hokkanen]

This is a good idea. The working RMM version with CUDA 11 patch is currently available here: https://github.com/hokkanen/rmm.