Basic ideas:

• Add File field.
• Add FileType, FileLength (or reuse Length?) validators.
• Register some custom field converters.
• Update the spec based on the field type.

References:

• https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.0.3.md#considerations-for-file-uploads
• https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.0.3.md#special-considerations-for-multipart-content