0.46.0

Added the fixtures app. This is used to dump data from a database to a JSON file, and then reload it again. It's useful for seeding a database with essential data, whether that's a colleague setting up their local environment, or deploying to production.

To create a fixture:

piccolo fixtures dump --apps=blog > fixture.json

To load a fixture:

piccolo fixtures load fixture.json

As part of this change, Piccolo's Pydantic support was brought into this library (prior to this it only existed within the piccolo_api library). At a later date, the piccolo_api library will be updated, so it's Pydantic code just proxies to what's within the main piccolo library.