Update jupyter-scheduler version in nebari-docker-images

[marcelovilla]

Context

We're currently pinning jupyter-scheduler version to be lower than 2.6.0 to avoid jupyter-server/jupyter-scheduler#519. Since then, a new version has been released, addressing that particular issue: v2.7.0.

We just need to make sure the DB migration is not breaking anything on our side.

Value and/or benefit

Keep up-to-date with newer versions of our dependencies.

Anything else?

I'm tagging @krassowski and @viniciusdc to keep them in the loop.

[arjxn-py]

Hey, can I give it a try unless someone from the team start working on this one?
If yes, I'd be afraid to be assigned as I don't want to prevent anybody else working on this at the same time.
But I'd like to know, In order to locally test the infrastructure & to make sure the DB migration is not breaking after bumping the version - do I need to also have credits in some cloud provider?

I'd apologize in advance in case I'm not approaching this correctly, please correct me in that case. Thanks 💐