v2021.12.0

This release updates the notebooks and conda environments to work with RAPIDS version 2021.12.

1. The 70k lung cell and 1.3M neuron example notebooks no longer need to batch the PCA.
2. 1.3M neuron multi-gpu example notebook now performs umap inference, kmeans, and PCA across multiple gpus.
3. 1.3M neuron notebooks now contain differential gene expression analysis.