`/context` does not work due to small model mismatch

## Problem

```
> /context
⎿ Error: 404 {"error":{"code":404,"message":"Publisher Model `projects/dev-ai-gamma/locations/us-east5/publishers/anthropic/models/claude-3-5-haiku@20241022`
was not found or your project does not have access to it. Please ensure you are using a valid model version. For more information, see:
https://cloud.google.com/vertex-ai/generative-ai/docs/learn/model-versions","status":"NOT_FOUND"}}
```

## Solution

Probably need to update the small model name here:

https://github.com/juspay/vertex/blob/f77aae91d7e94aaa997e2478c8c4173a5f67a52a/package.nix#L12