Bump idna from 2.9 to 2.10

Bumps [idna](https://github.com/kjd/idna) from 2.9 to 2.10.
- [Release notes](https://github.com/kjd/idna/releases)
- [Changelog](https://github.com/kjd/idna/blob/master/HISTORY.rst)
- [Commits](kjd/idna@v2.9...v2.10)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Author: dependabot-preview[bot]

requirements.txt

@@ -12,7 +12,7 @@ attrs==19.3.0             # via aiohttp
 cffi==1.14.0              # via pycares
 chardet==3.0.4            # via aiohttp
 fonttools==4.12.1          # via fdiff (setup.py)
-idna==2.9                 # via yarl
+idna==2.10                 # via yarl
 multidict==4.7.6          # via aiohttp, yarl
 pycares==3.1.1            # via aiodns
 pycparser==2.20           # via cffi