Bump idna from 2.10 to 3.7

Bumps [idna](https://github.com/kjd/idna) from 2.10 to 3.7.
- [Release notes](https://github.com/kjd/idna/releases)
- [Changelog](https://github.com/kjd/idna/blob/master/HISTORY.rst)
- [Commits](kjd/idna@v2.10...v3.7)

---
updated-dependencies:
- dependency-name: idna
  dependency-type: direct:production
...

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

requirements.txt

@@ -10,7 +10,7 @@ discord.py==1.6.0
 dnspython==2.0.0
 humanfriendly==4.7
 humanize==3.2.0
-idna==2.10
+idna==3.7
 import-expression==1.1.4
 jishaku==1.20.0.220
 motor==2.3.0