Bump idna from 3.4 to 3.7 in /doc

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: direct:production
...

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

doc/requirements.txt

@@ -3,7 +3,7 @@ Babel==2.12.1
 certifi==2023.7.22
 charset-normalizer==3.2.0
 docutils==0.17.1
-idna==3.4
+idna==3.7
 imagesize==1.4.1
 Jinja2==3.1.3
 latexcodec==2.0.1