Bump pallets-sphinx-themes from 2.0.3 to 2.1.0

Bumps [pallets-sphinx-themes](https://github.com/pallets/pallets-sphinx-themes) from 2.0.3 to 2.1.0.
- [Release notes](https://github.com/pallets/pallets-sphinx-themes/releases)
- [Changelog](https://github.com/pallets/pallets-sphinx-themes/blob/main/CHANGES.rst)
- [Commits](https://github.com/pallets/pallets-sphinx-themes/compare/2.0.3...2.1.0)

---
updated-dependencies:
- dependency-name: pallets-sphinx-themes
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

requirements-dev.txt

@@ -6,7 +6,7 @@ pylint==2.17.2
 splinter==0.19.0
 selenium==4.9.0
 twine==4.0.2
-Pallets-Sphinx-Themes==2.0.3
+Pallets-Sphinx-Themes==2.1.0
 Sphinx==6.2.1
 sphinx-issues==3.0.1
 sphinx-jinja==2.0.2