feat(auth0): Add upsert_user function

[talevy42]

Adds upsert_user function to the Auth0 connector.

[shaunagm]

Hi @talevy42! Thank you so much for adding this. Can you also add a corresponding test? (If you haven't written a Parsons test before, this guide may be helpful. It's written for people building entirely new connectors, so you can skip a bunch of the setup stuff, but it goes over things like how mocks work, etc.

[talevy42]

Added a test based on what I saw in other connector tests for upsert!

[talevy42]

I'm not certain what's causing the build error here. CircleCI is saying Python3 is not found

[shaunagm]

Thanks for adding the test! Not sure why the automatic checks were failing, but they're working now, so I'll merge this. Thanks again @talevy42!