Upgrade litellm, suppress bugs (#506)

Author: arcticfly

docs/fundamentals/ruler.mdx

@@ -335,3 +335,7 @@ for traj in judged_group.trajectories:
 
 - Use cheaper judge models (e.g., Qwen3 32B)
 - Reduce group size
+
+<Note>
+Since RULER uses LiteLLM under the hood, ART automatically suppresses harmless Pydantic serialization warnings from LiteLLM ([related issue](https://github.com/BerriAI/litellm/issues/11759)). To disable this behavior, set `SUPPRESS_LITELLM_SERIALIZATION_WARNINGS=0` in your environment.
+</Note>

pyproject.toml

@@ -7,7 +7,7 @@ requires-python = ">=3.11"
 dependencies = [
     "openai>=2.14.0",
     "typer>=0.15.2",
-    "litellm==1.74.1",
+    "litellm>=1.74.1",
     "weave>=0.51.51",
     "tinker>=0.7.0",
     "tinker-cookbook>=0.1.0",

src/art/__init__.py

@@ -1,5 +1,16 @@
 import os
 
+from dotenv import load_dotenv
+
+load_dotenv()
+
+if os.getenv("SUPPRESS_LITELLM_SERIALIZATION_WARNINGS", "1") == "1":
+    from art.utils.suppress_litellm_serialization_warnings import (
+        suppress_litellm_serialization_warnings,
+    )
+
+    suppress_litellm_serialization_warnings()
+
 # Create a dummy GuidedDecodingParams class and inject it into vllm.sampling_params for trl compatibility
 try:
     import vllm.sampling_params

src/art/utils/suppress_litellm_serialization_warnings.py

@@ -0,0 +1,22 @@
+import warnings
+
+
+def suppress_litellm_serialization_warnings():
+    """
+    Suppress litellm's internal Pydantic serialization warnings.
+
+    These warnings occur due to a known litellm issue (#11759) where response
+    types (Message, StreamingChoices) have mismatched field counts during
+    internal serialization. The warnings don't affect functionality.
+
+    Scoped to only silence:
+    - UserWarning category
+    - From pydantic.main module
+    - Matching "Pydantic serializer warnings: PydanticSerializationUnexpectedValue"
+    """
+    warnings.filterwarnings(
+        "ignore",
+        category=UserWarning,
+        module=r"pydantic\.main",
+        message=r"Pydantic serializer warnings:\s+PydanticSerializationUnexpectedValue",
+    )