Update idna to 3.0

[pyup-bot]

This PR updates idna from 2.10 to 3.0.

Changelog

3.0

++++++++++++++++

- Python 2 is no longer supported (the 2.x branch supports Python 2,
use "idna<3" in your requirements file if you need Python 2 support)
- Support for V2 UTS 46 test vectors.

Links

• PyPI: https://pypi.org/project/idna
• Changelog: https://pyup.io/changelogs/idna/
• Repo: https://github.com/kjd/idna

[codecov-io]

Codecov Report

Merging #48 (d959034) into master (4a4a665) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master       #48   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           12        12           
  Lines          116       116           
=========================================
  Hits           116       116           

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[pyup-bot]

Closing this in favor of #49