Make run_activity function asynchronous in activity_as_tool

Author: AnatoliB

samples-v2/openai_agents/tools.py

@@ -30,7 +30,7 @@ def activity_as_tool(context: DurableAIAgentContext, activity_func: Callable) ->
 
     activity_name = activity_func._function._name
 
-    def run_activity(ctx: RunContextWrapper[Any], input: str) -> Any:
+    async def run_activity(ctx: RunContextWrapper[Any], input: str) -> Any:
         result = context.get_activity_call_result(activity_name, input)
         return result