Bump idna from 2.10 to 3.0

Bumps idna from 2.10 to 3.0.

Changelog

Sourced from idna's changelog.

3.0 (2021-01-01) ++++++++++++++++

• 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.

Commits

• a45bf88 Release v3.0
• 82f7b70 Fix regressions from removing Python 2 support
• 229f123 Use Github Actions for unit testing
• d8bb757 Merge pull request #90 from kjd/fix-licensing
• a2f5460 Merge branch 'master' into fix-licensing
• 537aa99 Add 3-clause BSD license that Github can detect
• 6dc4bfb Merge pull request #89 from jdufresne/py39
• 153b5ab Use Python 3.9 release in Travis configuration
• cc273f8 Merge pull request #88 from hugovk/add-3.9
• 4b3e6fd Remove redundant Python 2 code
• Additional commits viewable in compare view