Force Claude 3 models to output JSON object and parse it more reliably (#293)

Co-authored-by: otmane <otmanebenazzou.pro@gmail.com>

skyvern/forge/sdk/api/llm/models.py

@@ -10,6 +10,7 @@ class LLMConfig:
     model_name: str
     required_env_vars: list[str]
     supports_vision: bool
+    add_assistant_prefix: bool
 
     def get_missing_env_vars(self) -> list[str]:
         missing_env_vars = []