Bump readthedocs-sphinx-search from 0.2.0 to 0.3.1

Bumps [readthedocs-sphinx-search](https://github.com/readthedocs/readthedocs-sphinx-search) from 0.2.0 to 0.3.1.
- [Release notes](https://github.com/readthedocs/readthedocs-sphinx-search/releases)
- [Changelog](https://github.com/readthedocs/readthedocs-sphinx-search/blob/main/CHANGELOG.rst)
- [Commits](https://github.com/readthedocs/readthedocs-sphinx-search/commits)

---
updated-dependencies:
- dependency-name: readthedocs-sphinx-search
  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 @@
 sphinx==5.3.0
 sphinx_rtd_theme==1.2.0
-readthedocs-sphinx-search==0.2.0
+readthedocs-sphinx-search==0.3.1