⬆️ Update sphinx-rtd-theme requirement from ~=2.0 to ~=3.0

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...3.0.2)

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

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

pyproject.toml

@@ -61,7 +61,7 @@ docs = [
 theme-im = ["sphinx-immaterial~=0.11.11"]
 theme-furo = ["furo~=2024.8.6"]
 theme-pds = ["pydata-sphinx-theme~=0.15.2"]
-theme-rtd = ["sphinx_rtd_theme~=2.0"]
+theme-rtd = ["sphinx_rtd_theme~=3.0"]
 
 [dependency-groups]
 dev = ["pre-commit~=3.0", "tox~=4.23", "tox-uv~=1.15"]