Log Message:
py-nbformat: updated to 5.0.6

5.0.6
=====
- nbformat.read() function has a better duck-type interface and will raise more
  meaningful error messages if it can't parse a notebook document.

5.0.5
=====
- Allow notebook format 4.0 and 4.1 to have the arbitrary JSON mimebundles
  from format 4.2 for pragmatic purposes.
- Support reading/writing path-like objects has been added to read operations.

5.0.4
=====
- Fixed issue causing python 2 to pick up 5.0.x releases.

5.0.3
=====
- Removed debug print statements from project.

5.0.2
=====
- Added schema validation files for older versions. This was breaking notebook \ 
generation.

5.0
===
`5.0 on GitHub <https://github.com/jupyter/nbformat/milestone/5>`__

- Starting with 5.0, ``nbformat`` is now Python 3 only (>= 3.5)
- Add execution timings in code cell metadata for v4 spec.
  ``"metadata": { "execution": {...}}`` should be populated \ 
with kernel-specific
  timing information.
- Documentation for how markup is used in notebooks added
- Link to json schema docs from format page added
- Documented the editable metadata flag
- Update description for collapsed field
- Documented notebook format versions 4.0-4.3 with accurate json schema \ 
specification files
- Clarified info about :ref:`name`'s meaning for cells
- Added a default execution_count of None for new_output_cell('execute_result')
- Added support for handling nbjson kwargs
- Wheels now correctly have a LICENSE file
- Travis builds now have a few more execution environments