Bump idna from 3.4 to 3.7 in /docs

Bumps [idna](https://github.com/kjd/idna) from 3.4 to 3.7.
- [Release notes](https://github.com/kjd/idna/releases)
- [Changelog](https://github.com/kjd/idna/blob/master/HISTORY.rst)
- [Commits](kjd/idna@v3.4...v3.7)

---
updated-dependencies:
- dependency-name: idna
  dependency-type: indirect
...

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

docs/requirements.txt

@@ -20,7 +20,7 @@ docutils==0.20.1
     #   sphinx
 furo==2023.8.17
     # via -r requirements.in
-idna==3.4
+idna==3.7
     # via requests
 imagesize==1.4.1
     # via sphinx