fix(docs): rename mkdocstrings 'import' option to 'inventories'

The mkdocstrings-python handler renamed its 'import' configuration
key to 'inventories'. With the pinned mkdocstrings[python]==0.30.1,
mkdocs build fails with 'PythonConfig.__init__() got an unexpected
keyword argument import', breaking the Read the Docs publication.

Author: bugfix-mission

mkdocs.yml

@@ -71,7 +71,7 @@ plugins:
       handlers:
         python:
           # Set up cross-references to Python types
-          import:
+          inventories:
             - https://docs.python.org/3/objects.inv
           paths: [src]
           options: