chore(deps): update dependency sphinx to v9

Author: renovate[bot]

requirements-dev.txt

@@ -4,7 +4,7 @@ tox==4.32.0 ; python_version >= "3.10"
 tox==4.32.0 ; python_version < "3.10"
 wheel==0.46.1
 Sphinx==9.0.4 ; python_version >= "3.11"
-Sphinx==7.4.7 ; python_version < "3.11"
+Sphinx==9.0.4 ; python_version < "3.11"
 sphinx-rtd-theme==3.1.0rc1 ; python_version >= "3.11"
 sphinx-rtd-theme==3.0.2 ; python_version < "3.11"
 pypandoc==1.16.2