fix: bound TypeAdapter lru_cache to prevent memory leak in multi-threaded usage

Author: giulio-leone

src/openai/_models.py

@@ -799,7 +799,7 @@ class GenericModel(BaseGenericModel, BaseModel):
 if not PYDANTIC_V1:
     from pydantic import TypeAdapter as _TypeAdapter
 
-    _CachedTypeAdapter = cast("TypeAdapter[object]", lru_cache(maxsize=None)(_TypeAdapter))
+    _CachedTypeAdapter = cast("TypeAdapter[object]", lru_cache(maxsize=4096)(_TypeAdapter))
 
     if TYPE_CHECKING:
         from pydantic import TypeAdapter