Added Configurable Exception Handler via Backoff Library

[xzrderek]

simple one:

    exception_handler_config=ExceptionHandlerConfig(
        retryable_exceptions={
            litellm.RateLimitError,
            litellm.APIConnectionError,
        }
    ),

sophisticated one:

def api_retry_strategy(e):
    """Sophisticated retry logic for API calls"""
    if isinstance(e, litellm.AuthenticationError):
        return True  # Don't retry auth failures
    if isinstance(e, litellm.RateLimitError):
        return False  # Always retry rate limits
    if hasattr(e, 'response'):
        status = e.response.status_code
        return 400 <= status < 500 and status != 429  # Retry 429 but not other 4xx
    return False

@evaluation_test(
    completion_params=[{"model": "gpt-4o-mini"}],
    input_messages=[[Message(role="user", content="Test")]],
    exception_handler_config=ExceptionHandlerConfig(
        retryable_exceptions={
            litellm.RateLimitError,
            litellm.InternalServerError,
            litellm.APIConnectionError,
            requests.exceptions.RequestException,
        },
        backoff_config=BackoffConfig(
            strategy="expo",
            max_tries=7,
            base_delay=1.0,
            max_delay=120.0,
            factor=1.5,
            giveup_func=api_retry_strategy,
        )
    ),
)
def advanced_api_test(rows): ...