Update python-nbformat to version 5.4.0 / rev 11 via SR 992642
https://build.opensuse.org/request/show/992642
by user bnavigator + dimstar_suse
- Update to 5.4.0
* Fix import nbformat.current by @shadchin in #269
* Add mypy support by @blink1073 in #270
* Packaging updates