Bump idna from 2.10 to 3.1

Bumps [idna](https://github.com/kjd/idna) from 2.10 to 3.1.
- [Release notes](https://github.com/kjd/idna/releases)
- [Changelog](https://github.com/kjd/idna/blob/master/HISTORY.rst)
- [Commits](kjd/idna@v2.10...v3.1)

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

requirements.txt

@@ -8,7 +8,7 @@ cffi==1.14.2
 chardet==3.0.4
 cryptography==3.3.2
 gunicorn==20.0.4
-idna==2.10
+idna==3.1
 multidict==4.7.6
 pycparser==2.20
 six==1.15.0