Bump sphinx-rtd-theme from 0.5.0 to 0.5.1

Bumps [sphinx-rtd-theme](https://github.com/readthedocs/sphinx_rtd_theme) from 0.5.0 to 0.5.1.
- [Release notes](https://github.com/readthedocs/sphinx_rtd_theme/releases)
- [Changelog](https://github.com/readthedocs/sphinx_rtd_theme/blob/master/docs/changelog.rst)
- [Commits](readthedocs/sphinx_rtd_theme@0.5.0...0.5.1)

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

docs_requirements.txt

@@ -66,7 +66,7 @@ six==1.15.0
 snowballstemmer==2.0.0
 Sphinx==3.3.1
 sphinx-jsonschema==1.16.6
-sphinx-rtd-theme==0.5.0
+sphinx-rtd-theme==0.5.1
 sphinxcontrib-applehelp==1.0.2
 sphinxcontrib-devhelp==1.0.2
 sphinxcontrib-htmlhelp==1.0.3