fix doc building with new sphinx

Author: tomato42

docs/source/conf.py

@@ -62,7 +62,9 @@
 html_static_path = ["_static"]
 
 # Example configuration for intersphinx: refer to the Python standard library.
-intersphinx_mapping = {"https://docs.python.org/": None}
+intersphinx_mapping = {
+    'python': ("https://docs.python.org/", None),
+}
 
 autodoc_default_options = {
     "undoc-members": True,