Support attrs 23.2.0

[yasirroni]

Currently, pytest-notebook limited to the following dependency:

pytest-notebook 0.6.1 requires attrs<21,>=19, but you have attrs 23.2.0 which is incompatible.
pytest-notebook 0.6.1 requires nbconvert~=5.6.0, but you have nbconvert 7.16.4 which is incompatible.

Is there any conflict that cause us to not upgrade the dependency? Thank you.