fix workflow_runs.code_gen to enforce code generate only for task v2 block run (#3597)

skyvern/services/workflow_service.py

@@ -23,6 +23,7 @@ async def prepare_workflow(
     max_steps: int | None = None,
     request_id: str | None = None,
     debug_session_id: str | None = None,
+    code_gen: bool | None = None,
 ) -> WorkflowRun:
     """
     Prepare a workflow to be run.
@@ -40,6 +41,7 @@ async def prepare_workflow(
         max_steps_override=max_steps,
         is_template_workflow=template,
         debug_session_id=debug_session_id,
+        code_gen=code_gen,
     )
 
     workflow = await app.WORKFLOW_SERVICE.get_workflow_by_permanent_id(