Bump pydata-sphinx-theme from 0.18.0 to 0.20.0

Bumps [pydata-sphinx-theme](https://github.com/pydata/pydata-sphinx-theme) from 0.18.0 to 0.20.0.
- [Release notes](https://github.com/pydata/pydata-sphinx-theme/releases)
- [Changelog](https://github.com/pydata/pydata-sphinx-theme/blob/main/RELEASE.md)
- [Commits](pydata/pydata-sphinx-theme@v0.18.0...v0.20.0)

---
updated-dependencies:
- dependency-name: pydata-sphinx-theme
  dependency-version: 0.17.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

docs/requirements.txt

@@ -4,5 +4,5 @@ sphinx-book-theme
 sphinxcontrib-mermaid
 myst-parser>=5.1.0
 breathe>=4.36.0
-pydata-sphinx-theme==0.18.0
+pydata-sphinx-theme==0.20.0
 pydoc-markdown>=4.8.2