Python 3.9 support

[djkapner]

• [ ] Await word/release from PyNWB about python 3.9 support (h5py 3)
• [ ] add python 3.9 to cloud test matrix
• [ ] add python 3.9 to anaconda3 docker and bamboo strategies.
• [ ] resolve any dependency conflcts
• [ ] pass builds on github-actions
• [ ] pass builds on on-prem tests