Unit tests for `validate_images`

[AetherUnbound]

Description

Add unit tests for the validate_images function:

https://github.com/WordPress/openverse-api/blob/v2.5.10/api/catalog/api/utils/validate_images.py#L21

Additional context

Part of a series of unit test issues (see https://github.com/WordPress/openverse-api/issues/871 & https://github.com/WordPress/openverse-api/issues/873)

Implementation

• [ ] 🙋 I would be interested in implementing this feature.

[Rajarshi1998]

I would like to contribute to fix this issue. Thank you!!

[dhruvkb]

@Rajarshi1998 sure, go ahead. I'm assigning this to you. If you need any help getting started, you can leave a comment here or send a message to the #openverse channel in the Making WordPress Slack workspace.