Bump pydata-sphinx-theme from 0.6.3 to 0.16.1

Bumps [pydata-sphinx-theme](https://github.com/pydata/pydata-sphinx-theme) from 0.6.3 to 0.16.1.
- [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@v0.6.3...v0.16.1)

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

Signed-off-by: dependabot[bot] <[email protected]>

docs/requirements.txt

@@ -1,2 +1,2 @@
 Sphinx==4.1.2
-pydata-sphinx-theme==0.6.3
+pydata-sphinx-theme==0.16.1