([Full Changelog](https://github.com/jupyter/notebook/compare/v6.4.4...ccd9665571107e02a325a738b8baebd6532b2d3d))
Bug fixes
- Recover from failure to render mimetype [6181](https://github.com/jupyter/notebook/pull/6181) ([martinRenou](https://github.com/martinRenou))
Maintenance and upkeep improvements
- Fix crypto handling [6197](https://github.com/jupyter/notebook/pull/6197) ([blink1073](https://github.com/blink1073))
- Fix `jupyter_client` warning [6178](https://github.com/jupyter/notebook/pull/6178) ([martinRenou](https://github.com/martinRenou))
Documentation improvements
- Fix nbsphinx settings [6200](https://github.com/jupyter/notebook/pull/6200) ([mgeier](https://github.com/mgeier))
- Fully revert the pinning of `nbsphinx` to 0.8.6 [6201](https://github.com/jupyter/notebook/pull/6201) ([kevin-bates](https://github.com/kevin-bates))
- Pin `nbsphinx` to 0.8.6, clean up orphaned resources [6194](https://github.com/jupyter/notebook/pull/6194) ([kevin-bates](https://github.com/kevin-bates))
- Fix typo in docstring [6188](https://github.com/jupyter/notebook/pull/6188) ([jgarte](https://github.com/jgarte))
Contributors to this release
([GitHub contributors page for this release](https://github.com/jupyter/notebook/graphs/contributors?from=2021-09-03&to=2021-10-19&type=c))
[blink1073](https://github.com/search?q=repo%3Ajupyter%2Fnotebook+involves%3Ablink1073+updated%3A2021-09-03..2021-10-19&type=Issues) | [jgarte](https://github.com/search?q=repo%3Ajupyter%2Fnotebook+involves%3Ajgarte+updated%3A2021-09-03..2021-10-19&type=Issues) | [kevin-bates](https://github.com/search?q=repo%3Ajupyter%2Fnotebook+involves%3Akevin-bates+updated%3A2021-09-03..2021-10-19&type=Issues) | [martinRenou](https://github.com/search?q=repo%3Ajupyter%2Fnotebook+involves%3AmartinRenou+updated%3A2021-09-03..2021-10-19&type=Issues) | [mgeier](https://github.com/search?q=repo%3Ajupyter%2Fnotebook+involves%3Amgeier+updated%3A2021-09-03..2021-10-19&type=Issues)