ipywidgets: update 7.6.3 to 7.6.4

[dkomisar]

• upstream repo https://github.com/jupyter-widgets/ipywidgets
• run tests on dependent packages
  • build jupyter with new ipywidgets
• go through changelog
  • changelog only calls out major version changes - diff between 7.6.3..7.6.4
• look for any open issues for new versions
  • too many open issues to look but none contain the text 7.6.4
• dev_url, doc_url valid
• setuptools/wheel/pip/pip check included
• compare pinned versions from upstream github setup

setup.cfg
        'Programming Language :: Python',
        'Programming Language :: Python :: 2.7',
        'Programming Language :: Python :: 3',
        'Programming Language :: Python :: 3.3',
        'Programming Language :: Python :: 3.4',
        'Programming Language :: Python :: 3.5',
    'ipykernel>=4.5.1',
    'ipython_genutils~=0.2.0',
    'traitlets>=4.3.1',
    'nbformat>=4.2.0',
    'widgetsnbextension~=3.5.0'
    ':python_version<"3.3"' : ['ipython>=4.0.0,<6.0.0'],
    ':python_version>="3.3"': ['ipython>=4.0.0'],
    ':python_version>="3.6"': ['jupyterlab_widgets>=1.0.0'],

meta.yaml
    - ipython >=4.0.0
    - ipykernel >=4.5.1
    - traitlets >=4.3.1,<6.0.0
    - nbformat >=4.2.0
    - widgetsnbextension >=3.5.0,<3.6.0
    - jupyterlab_widgets >=1.0.0

[dkomisar]

diff mentions adding ipython_genutils as an explicit dependency, and this was also done by conda forge.
jupyter-widgets/ipywidgets@a7629a3
package builds fine without it though, so maybe tests don't cover it.

[jasongrout]

See jupyter-widgets/ipywidgets#3262 for why we added the dependency

[katietz]

Thanks for the heads up