bad defaults for due date date/time picker

[clhedrick]

Operating system

ubuntu 22.04

nbgrader --version

0.9.2

jupyterhub --version (if used with JupyterHub)

4.1.5

jupyter notebook --version

jupyterlab 4.1.8

Expected behavior

I have lots of due dates with random times. Faculty aren't realizing that the defaults are the current date time, so they set the date only. I think it would make more sense to default to midnight for a new due date, although obviously if you're adjusting an existing one it should default to the current due date.

Having UTC the default is also odd. I'd expect it to default to local time. I've tried a couple of configuration settings and not found one that works.

Actual behavior

Steps to reproduce the behavior