Bump sphinx-hoverxref from 0.8b1 to 0.9b1 in /docs (#1142)

Bumps [sphinx-hoverxref](https://github.com/readthedocs/sphinx-hoverxref) from 0.8b1 to 0.9b1.
- [Release notes](https://github.com/readthedocs/sphinx-hoverxref/releases)
- [Changelog](https://github.com/readthedocs/sphinx-hoverxref/blob/master/CHANGELOG.rst)
- [Commits](https://github.com/readthedocs/sphinx-hoverxref/commits)

---
updated-dependencies:
- dependency-name: sphinx-hoverxref
  dependency-type: direct:production
...

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

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

Author: dependabot[bot]

docs/requirements.txt

@@ -5,7 +5,7 @@ sphinx==4.3.0
 sphinx_autodoc_typehints==1.12.0
 sphinxcontrib-mermaid==0.7.1
 sphinx-typlog-theme==0.8.0
-sphinx-hoverxref==0.8b1
+sphinx-hoverxref==0.9b1
 recommonmark==0.7.1
 m2r==0.2.1
 tomlkit==0.7.2