Bump idna from 2.8 to 2.9

Bumps [idna](https://github.com/kjd/idna) from 2.8 to 2.9.
- [Release notes](https://github.com/kjd/idna/releases)
- [Changelog](https://github.com/kjd/idna/blob/master/HISTORY.rst)
- [Commits](kjd/idna@v2.8...v2.9)

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

requirements.txt

@@ -1,6 +1,6 @@
 certifi==2019.11.28
 chardet==3.0.4
-idna==2.8
+idna==2.9
 requests==2.22.0
 Unidecode==1.1.1
 urllib3==1.25.8