new release for 5.x to address a SyntaxWarning? (Edit: also 4.3.x)

👋 colleagues! i just wondered when you may push a 5.x release to pip and conda forge. Right now with python 3.8 traitlets is throwing some warnings that are causing some issues with our builds (see below). i see that pip and conda forge as using 4.x. i see 3 release bundles here for 5.x! AND int hat bundle see a fix here in the repo.
```
Executing: 100% 34/34 [00:06<00:00, 4.86cell/s]
/opt/conda/lib/python3.8/site-packages/traitlets/config/loader.py:795: SyntaxWarning: "is" with a literal. Did you mean "=="?
if len(key) is 1:
```

thank you for any help or info!
Leah