Bump furo from 2022.4.7 to 2022.9.15 in /docs

Bumps [furo](https://github.com/pradyunsg/furo) from 2022.4.7 to 2022.9.15.
- [Release notes](https://github.com/pradyunsg/furo/releases)
- [Changelog](https://github.com/pradyunsg/furo/blob/main/docs/changelog.md)
- [Commits](pradyunsg/furo@2022.04.07...2022.09.15)

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

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

Author: dependabot[bot]

docs/requirements.txt

@@ -1,4 +1,4 @@
-furo==2022.4.7
+furo==2022.9.15
 sphinx==4.5.0
 sphinx-click==4.3.0
 myst_parser==0.17.2