This reverts commit 73e061c8.

Remove PDF engine option in file imports

See merge request !769

Add a ModelAdmin for Revision instead of an inline

Closes #275

See merge request !771

Remove make api-schema

See merge request !768

Allow an element's parent field to be set to null

See merge request !767

Remove redundant OpenAPI CI job

See merge request !765

The SchemaView unit tests already take care of testing the full schema generation;
this job wastes some CI time doing what the tests already do and does not provide
anything more than what a unit test can do.

Add APIStar requirements for schema generation

See merge request !764

Add ReDoc documentation

Closes #265

See merge request !762

Prevent transcriptions without a zone to be added to transcriptions ElasticSearch index

See merge request !763

Prevent creating a single transcription with a zone

See merge request !761

OpenAPI schema endpoint

Closes #264

See merge request !760

Prevent removing parameter overrides on first schema generation

See merge request !759

Nullable transcription zone

See merge request !756

Fix fixtures build

See merge request !757

Add make api-schema command

See merge request !758

Merge patch.py into the SchemaGenerator

Closes #254

See merge request !755

Direct image creation from info.json

See merge request !753

Add OpenAPI docs for email verification endpoint

See merge request !754

Avoid empty FRONTEND_VERSION with the new config style

See merge request !752

Replace local_settings.py by config.yml in README.md

Closes #69

See merge request !751