Build(deps): Bump idna from 3.7 to 3.8 in /dependencies/docs

Bumps [idna](https://github.com/kjd/idna) from 3.7 to 3.8.
- [Release notes](https://github.com/kjd/idna/releases)
- [Changelog](https://github.com/kjd/idna/blob/master/HISTORY.rst)
- [Commits](kjd/idna@v3.7...v3.8)

---
updated-dependencies:
- dependency-name: idna
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

dependencies/docs/constraints.txt

@@ -3,7 +3,7 @@ Babel==2.16.0
 certifi==2024.7.4
 charset-normalizer==3.3.2
 docutils==0.20.1
-idna==3.7
+idna==3.8
 imagesize==1.4.1
 Jinja2==3.1.4
 MarkupSafe==2.1.5