Bump furo from 2024.1.29 to 2024.5.6 in /docs

Bumps [furo](https://github.com/pradyunsg/furo) from 2024.1.29 to 2024.5.6.
- [Release notes](https://github.com/pradyunsg/furo/releases)
- [Changelog](https://github.com/pradyunsg/furo/blob/main/docs/changelog.md)
- [Commits](pradyunsg/furo@2024.01.29...2024.05.06)

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

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

docs/requirements.txt

@@ -1,3 +1,3 @@
-furo==2024.1.29
+furo==2024.5.6
 sphinx==7.2.6
 myst_parser==2.0.0