[3.11] Docs: upgrade to python-docs-theme 2023.7 (pythonGH-107617)

(cherry picked from commit 19f32b2)

Co-authored-by: Hugo van Kemenade <[email protected]>

Doc/requirements.txt

@@ -15,6 +15,6 @@ sphinxext-opengraph>=0.7.1
 
 # The theme used by the documentation is stored separately, so we need
 # to install that as well.
-python-docs-theme>=2022.1
+python-docs-theme>=2023.7
 
 -c constraints.txt