Release planning for 6.1.0

[consideRatio]

KubeSpawner would benefit greatly from a release with #742 in it, what I think was a regression from previous major versions of KubeSpawner. Z2JH 3.0.0 - 3.0.3 users are affected by it. The consequences of this bug is that user pods can be left running in k8s while JupyterHub thinks the servers are stopped, and this can incurr significant cloud costs. Users with a stranded server can still re-start it via JupyterHub though.

To make this release, we should also include notes on how users can cleanup such stranded servers intelligently. @minrk has made a script that inspects k8s resources and the jupyterhub state to help figure out what user servers should be considered for cleanup.

Todo

• Bug using profile_options when profile_list has entries named like short and short-plus #702, fixed by Fix for unlisted_choice, docstring updates, and misc refactoring #773
• return poll status after first load finish #742
• Support lists and dicts as values in kubespawner_override #785
• Don't sort keys by default in tojson when rendering profile forms #787
• Add changelog for 6.1.0 #768

Todo related to unlisted_choice

• API Calls to spawn user servers do not handle defaults in profileList correctly #758, fixed by [Bug] Setting unlisted_choice a second time has no effect #772
• Don't show dropdown in profile_options if only unlisted_choice is enabled, no choices are present #756, fixed by Refs #756: Handle no choices provided if unlisted_choice is present #778
• Allow configuring text shown in profile_option dropdown for selecting unlisted_choice #757

Todo considered outside the scope of this release

• Refactor out profile_list related logic from spawner.py #775