[ENH] - Move to JupyterHub 5.x (unreleased) to support app sharing

[aktech]

Feature description

We're using JupyterHub 4.0.1 right now and this is a proposal to upgrade JupyterHub from 4.x to 5.x (unreleased).

Value and/or benefit

Since the last release of JupyterHub (4.0.2). JupyterHub added the ability to share user servers, which is a crucial feature we would like to implement in jhub-apps, See: #11

We're looking for this feature (which is not available in 4.x):

• user-initiated sharing jupyterhub/jupyterhub#4594
• https://jupyterhub.readthedocs.io/en/latest/reference/rest-api.html#operation/post-shares-server

JupyterHub 5.x release might be around the corner, but I am not sure about the exact timeline right now. We will have to upgrade later anyways, upgrading now will unblock us from using sharing feature.

Anything else?

No response

[aktech]

This was done in:

• Add support for JupyterHub 5.0 #294
• Test on JupyterHub 5.0.0b1 and bump Python #248