Support newer versions of Python

[oliverchang]

The main blocker to this is our dependency on python libraries with C extensions (e.g. protobuf, grpc)), and the need to bundle them in our deployment zips across Linux, Windows, and Mac.

We should see if there's a way for us to set up cross platform build environments (e.g. leveraging GitHub actions) to build the these necessary dependencies into reusable Python wheels.

[oliverchang]

@jonathanmetzman wdyt?