Implement scDeepSort

[AleksBekker]

• Reference-based
• Paper: 10.1038/s41587-019-0113-3
• Code: https://github.com/ZJUFanLab/scDeepSort
• Documentation: https://scanpy-tutorials.readthedocs.io/en/latest/spatial/integration-scanorama.html

[AleksBekker]

Problem: this is only available on Python 3.7, while other packages (such as celltypist and scVI) must be on 3.8+