Bump furo from 2022.4.7 to 2022.6.21 (#1760)

Bumps [furo](https://github.com/pradyunsg/furo) from 2022.4.7 to 2022.6.21.
- [Release notes](https://github.com/pradyunsg/furo/releases)
- [Changelog](https://github.com/pradyunsg/furo/blob/main/docs/changelog.md)
- [Commits](https://github.com/pradyunsg/furo/compare/2022.04.07...2022.06.21)

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

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

setup.py

@@ -65,7 +65,7 @@ setup(
     setup_requires=["pytest-runner"],
     extras_require={
         "docs": [
-            "furo==2022.4.7",
+            "furo==2022.6.21",
             "sphinx-autobuild",
             "codespell",
             "blacken-docs",