TST BUG: Tests fail in sandboxed environment

Almost all the tests fail inside a sandboxed build environment because they require network access for some reason. The error is always the same:

```
python3.10-sphinx-automodapi> Warning, treated as error:
python3.10-sphinx-automodapi> failed to reach any of the inventories with the following issues:
python3.10-sphinx-automodapi> intersphinx inventory 'https://docs.python.org/3/objects.inv' not fetchable due to : HTTPSConnectionPool(host='docs.python.org', port=443): Max retries exceeded with url: /3/objects.inv (Caused by NewConnectionError(': Failed to establish a new connection: [Errno -3] Temporary failure in name resolution'))
```

I would appreciate it if there was a way to manually provide this `objects.inv` file, so that tests could still run without network access.

Start by running the test suite in a network-disabled sandbox and inspect the Sphinx intersphinx configuration responsible for fetching https://docs.python.org/3/objects.inv. Determine how to provide that inventory locally; done means the tests pass without network access while preserving the documented inventory behavior.

Written by the indexing model from the issue text.