Update python-dateutil to 2.7.4 (#1266)
Update python-dateutil to 2.7.4 (#1266)

This PR updates [python-dateutil](https://pypi.org/project/python-dateutil) from **2.7.3** to **2.7.4**.



*The bot wasn't able to find a changelog for this release. [Got an idea?](https://github.com/pyupio/changelogs/issues/new)*

<details>
  <summary>Links</summary>
  
  - PyPI: https://pypi.org/project/python-dateutil
  - Changelog: https://pyup.io/changelogs/python-dateutil/
  - Docs: https://dateutil.readthedocs.io
</details>


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