Update schema and mocked images

[dhruvkb]

Fixes #65.

This PR updates the schema.sql and mocked_images.csv files by taking a fresh pg_dump from the new PostgreSQL 13.2 container.

The dumps were generated by executing the update_mocks.sh script.

Notable differences:

• The updated schema for the table public.image now matches the changes made to the Image model in Django.
• The schema for the sequence public.image_id_seq is not present in the dump.
• All the indices have changed and now have temp_ prefix and _idx1 suffix.
• The mocked_images.csv also matches the updated schema in schema.sql.

[zackkrida]

Great work. It looks like the https://github.com/WordPress/openverse-api/blob/d51e38ed3b609d0f6fa668a7ef3420b556b77aa7/ingestion_server/test/mock_data/no_constraints_schema.sql is also using Postgres 10.3, could you explore that too?

[zackkrida]

very nice, thanks!