Bump sphinx-rtd-theme from 2.0.0rc2 to 2.0.0rc4

Bumps [sphinx-rtd-theme](https://github.com/readthedocs/sphinx_rtd_theme) from 2.0.0rc2 to 2.0.0rc4.
- [Changelog](https://github.com/readthedocs/sphinx_rtd_theme/blob/master/docs/changelog.rst)
- [Commits](readthedocs/sphinx_rtd_theme@2.0.0rc2...2.0.0rc4)

---
updated-dependencies:
- dependency-name: sphinx-rtd-theme
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

requirements/sphinx.txt

@@ -1,2 +1,2 @@
 Sphinx==7.2.6
-sphinx-rtd-theme==2.0.0rc2
+sphinx-rtd-theme==2.0.0rc4