Bump pydata-sphinx-theme from 0.15.2 to 0.15.3

Bumps [pydata-sphinx-theme](https://github.com/pydata/pydata-sphinx-theme) from 0.15.2 to 0.15.3.
- [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@v0.15.2...v0.15.3)

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

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

docs/requirements.txt

@@ -6,7 +6,7 @@ sphinx-argparse==0.4.0
 sphinx-copybutton==0.5.2
 meshio==5.3.5
 docutils==0.21.2
-pydata-sphinx-theme==0.15.2
+pydata-sphinx-theme==0.15.3
 sphinx-design==0.5.0
 setuptools>=65.5.1 # not directly required, pinned by Snyk to avoid a vulnerability
 pygments>=2.7.4 # not directly required, pinned by Snyk to avoid a vulnerability