text: Title: Tidy up tables used in Pydantic tests
  Body: We migrated the Pydantic code from Piccolo API - and now there's quite a mishmash of different tables in there (some are movie based, some are music based, and some are computer based). It might be worth standardising them a bit (for example, using music based tables like the rest of the tests).
  
  https://github.com/piccolo-orm/piccolo/blob/master/tests/utils/test_pydantic.py
  
  Not urgent, but a good first issue.