Update readthedocs-sphinx-search requirement in /requirements (#21)

Updates the requirements on [readthedocs-sphinx-search](https://github.com/readthedocs/readthedocs-sphinx-search) to permit the latest version.
- [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
...

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

Author: dependabot[bot]

requirements/docs.txt

@@ -4,5 +4,5 @@ sphinx-copybutton~=0.5.0
 furo==2023.9.10
 enum-tools[sphinx]~=0.11.0
 sphinx-design[furo]~=0.5.0
-readthedocs-sphinx-search~=0.3.0
+readthedocs-sphinx-search~=0.3.1
 sphinxcontrib-svg2pdfconverter~=1.2.0