py-nbformat: updated to 5.1.3

5.1.3
=====
- Change id generation to be hash based to avoid problematic word combinations
- Added tests for python 3.9
- Fixed setup.py build operations to include package data

5.1.2
=====
- Fixed missing file in manifest

5.1.1
=====
- Changes convert.upgrade to upgrade minor 4.x versions to 4.5

5.1.0
=====
- Implemented CellIds from JEP-62
- Fixed a regression introduced when using fastjsonschema,
  which does not directly support to validate a "reference"/"subschema"
- Removed unreachable/unneeded code
- Added CI workflow for package release on tag push

(adam)