Co-authored-by: Adam Johnson <me@adamj.eu>

Make it match the few lines above it.

Import from the documented location. Plus it's shorter.

Try to fix this error:

> Problem in your project's configuration. Invalid configuration option
> "build.os": build not found

For users who want to type `django_db_blocker` in their tests.

Scope it to the pytest config at least.

This also serves as a typing test.

This allows typing the `django_capture_on_commit_callbacks` fixture.

This allows typing the `django_assert_num_queries` and
`django_assert_max_num_queries` fixtures.