chore(deps): update sphinx-rtd-theme requirement

Updates the requirements on [sphinx-rtd-theme](https://github.com/readthedocs/sphinx_rtd_theme) to permit the latest version.
- [Changelog](https://github.com/readthedocs/sphinx_rtd_theme/blob/master/docs/changelog.rst)
- [Commits](readthedocs/sphinx_rtd_theme@2.0.0...3.0.0)

---
updated-dependencies:
- dependency-name: sphinx-rtd-theme
  dependency-type: direct:production
...

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

pyproject.toml

@@ -80,7 +80,7 @@ dev = [
 docs = [
     "sphinx >=7.0.0,<8.0.0",
     "sphinx-autodoc-typehints >=2.0.0,<3.0.0",
-    "sphinx-rtd-theme >=2.0.0,<3.0.0",
+    "sphinx-rtd-theme >=2.0.0,<4.0.0",
     "numpydoc >=1.5.0,<2.0.0",
     "sphinx_tabs >=3.4.1,<4.0.0",
     "sphinx-togglebutton >=0.3.2,<1.0.0",