Update sphinx-rtd-theme requirement from ^2.0.0 to >=2,<4

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:development
...

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

pyproject.toml

@@ -57,7 +57,7 @@ format-jinja = """
 
 [tool.poetry.group.docs.dependencies]
 sphinx = "^7.3.7"
-sphinx-rtd-theme = "^2.0.0"
+sphinx-rtd-theme = ">=2,<4"
 markdown-it-py = {version = "~3.0.0", extras = ["plugins"]}
 myst-parser = "^3.0.1"
 mdit-py-plugins = "^0.4.1"