build(deps-dev): bump sphinx-rtd-theme from 2.0.0 to 3.1.0 (#786)

Bumps [sphinx-rtd-theme](https://github.com/readthedocs/sphinx_rtd_theme) from 2.0.0 to 3.1.0.
- [Changelog](https://github.com/readthedocs/sphinx_rtd_theme/blob/master/docs/changelog.rst)
- [Commits](readthedocs/sphinx_rtd_theme@2.0.0...3.1.0)

---
updated-dependencies:
- dependency-name: sphinx-rtd-theme
  dependency-version: 3.1.0
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Fabian Hofmann <fab.hof@gmx.de>

Author: dependabot[bot]

pyproject.toml

@@ -56,8 +56,8 @@ remote = [
 docs = [
     "ipython==8.26.0",
     "numpydoc==1.7.0",
+    "sphinx_rtd_theme==3.1.0",
     "sphinx==9.0.4",
-    "sphinx_rtd_theme==2.0.0",
     "sphinx_book_theme==1.2.0",
     "sphinx-copybutton==0.5.2",
     "nbsphinx==0.9.4",