fix: err object has no attribute 'iter_lines' (#4686)

### What problem does this PR solve?

ERROR: 'Stream' object has no attribute 'iter_lines' with reference to
Claude/Anthropic chat streams

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

Co-authored-by: Kyle Olmstead <k.olmstead@offensive-security.com>

rag/llm/chat_model.py

                 stream=True,
                 **gen_conf,
             )
-            for res in response.iter_lines():
+            for res in response:
                 if res.type == 'content_block_delta':
                     text = res.delta.text
                     ans += text