Update idna to 2.8

[pyup-bot]

This PR updates idna from 2.7 to 2.8.

Changelog

2.8

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

- Update to Unicode 11.0.0.
- Provide more specific exceptions for some malformed labels.

Links

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

[codecov-io]

Codecov Report

Merging #76 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #76   +/-   ##
=======================================
  Coverage   36.41%   36.41%           
=======================================
  Files          32       32           
  Lines         552      552           
  Branches       24       24           
=======================================
  Hits          201      201           
  Misses        350      350           
  Partials        1        1

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[coveralls]

Pull Request Test Coverage Report for Build 308

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 33.833%

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Totals
Change from base Build 305:	0.0%
Covered Lines:	202
Relevant Lines:	552

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💛 - Coveralls