It looks like nbconvert CI on python 3.6 started failing about 3 weeks ago. There is a PR up to fix it by removing the python 3.6 test matrix  (this is because traitlets dropped support for python 3.6 and nbconvert depends on traitlets).
I’m keen to get this working again because I need another PR  downstream and don’t want to have to install from that branch as a workaround.
The concern I bring up in the CI fix is that if we’re no longer going to test on python 3.6 then
python_requires in setup.py should be bumped to require at least 3.7, there is a section in the README about support for 3.6 which should be dropped, and it looks like there should be a 6.1 release.
Since I’m not a regular contributor to this project I was wondering if there is something holding up making progress here so that the CI can be fixed and PRs can start flowing again? I’m happy to help in any way that I can if someone is needed to push buttons.
 Drop Python 3.6 and test with Python 3.9 by SylvainCorlay · Pull Request #1542 · jupyter/nbconvert · GitHub
 Allow get_export_names to skip configuration check by rmoe · Pull Request #1471 · jupyter/nbconvert · GitHub