fix: SphinxWarning

* SphinxWarning("The pre-Sphinx 1.0 'intersphinx_mapping' format is
  deprecated and will be removed in Sphinx 8. Update to the current format
  as described in the documentation. Hint: `intersphinx_mapping =
  {'<name>': ('https://docs.python.org/',
  None)}`.https://www.sphinx-doc.org/en/master/usage/extensions/intersphinx.html#confval-intersphinx_mapping")

docs/conf.py

@@ -2,7 +2,7 @@
 #
 # This file is part of Invenio.
 # Copyright (C) 2015-2018 CERN.
-# Copyright (C) 2022 Graz University of Technology.
+# Copyright (C) 2022-2024 Graz University of Technology.
 #
 # Invenio is free software; you can redistribute it and/or modify it
 # under the terms of the MIT License; see LICENSE file for more details.
@@ -11,10 +11,6 @@
 
 from __future__ import print_function
 
-import sys
-
-import sphinx.environment
-
 from invenio_jsonschemas import __version__
 
 # -- General configuration ------------------------------------------------
@@ -335,7 +331,9 @@
 
 
 # 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 configuraton.
 autoclass_content = "both"