fix(proxy_server.py): Fix "Circular reference detected" error when max_parallel_requests = 0 (#9671)

* fix(proxy_server.py): remove non-functional parent backoff/retry on /chat/completion

Causes circular reference error

* fix(http_parsing_utils.py): safely return parsed body - don't allow mutation of cached request body by client functions

Root cause fix for circular reference error

* Revert "fix: Anthropic prompt caching on GCP Vertex AI (#9605)" (#9670)

This reverts commit a8673246dc.

* add type hints for AnthropicMessagesResponse

* define types for response form AnthropicMessagesResponse

* fix response typing

* allow using litellm.messages.acreate and litellm.messages.create

* fix anthropic_messages implementation

* add clear type hints to litellm.messages.create functions

* fix anthropic_messages

* working anthropic API tests

* fixes - anthropic messages interface

* use new anthropic interface

* fix code quality check

* docs anthropic messages endpoint

* add namespace_packages = True to mypy

* fix mypy lint errors

* docs anthropic messages interface

* test: fix unit test

* test(test_http_parsing_utils.py): update tests

---------

Co-authored-by: Ishaan Jaff <ishaanjaffer0324@gmail.com>

litellm/proxy/proxy_server.py

@@ -3308,15 +3308,6 @@ async def model_list(
     tags=["chat/completions"],
     responses={200: {"description": "Successful response"}, **ERROR_RESPONSES},
 )  # azure compatible endpoint
-@backoff.on_exception(
-    backoff.expo,
-    Exception,  # base exception to catch for the backoff
-    max_tries=global_max_parallel_request_retries,  # maximum number of retries
-    max_time=global_max_parallel_request_retry_timeout,  # maximum total time to retry for
-    on_backoff=on_backoff,  # specifying the function to call on backoff
-    giveup=giveup,
-    logger=verbose_proxy_logger,
-)
 async def chat_completion(  # noqa: PLR0915
     request: Request,
     fastapi_response: Response,