Remove engine deprecations

[mmacia]

Hi, I fixed the library to support the latest API changes:

• Engines -> Models
• Removed deprecated search endpoint

Related #2

[crimson-knight]

@mmacia thank you for doing this!

@sferik any chance you can merge this? Would love to ensure the OpenAI client for Crystal is up to date since this is the shard that's referenced from the OpenAI docs

[mmacia]

I'm thinking of start a fork to implement all the new features and APIs but would be nice merge all the PRs here since the official documentation links to this repository.

[crimson-knight]

@mmacia yeah I think you're right, I maintain the Amber Framework and was working on a cli agent tool yesterday when I needed this. I found out it's end-points are outdated so it needs a decent bit of updating.

I can take your fork and put it into the Amber repo and see if we can get some community around it to help out