⬆️ 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@1.1.1...3.0.2)

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

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

pyproject.toml

@@ -57,7 +57,7 @@ sphinxcontrib-htmlhelp = "^2.1.0"
 sphinxcontrib-jsmath = "^1.0.1"
 sphinxcontrib-qthelp = "^1.0.8"
 sphinxcontrib-serializinghtml = "^1.1.10"
-sphinx-rtd-theme = ">=1.1.1,<3.0.0"
+sphinx-rtd-theme = ">=1.1.1,<4.0.0"
 sphinx-autodoc-typehints = ">=1.19.5,<3.0.0"
 autodocsumm = "^0.2.12"
 responses = ">=0.22,<0.26"