Update sphinx-rtd-theme requirement from ~=2.0.0 to ~=3.0.1

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...3.0.1)

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

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

requirements.txt

@@ -4,6 +4,6 @@
 Sphinx~=7.4
 doc8~=1.1.2
 reuse~=4.0.3
-sphinx-rtd-theme~=2.0.0
+sphinx-rtd-theme~=3.0.1
 sphinxcontrib-spelling~=8.0.0
 sphinx-multiversion~=0.2.4