Remove explicit lifetime to fix clippy-reported warning

src/controller/utils/agent.rs

@@ -10,8 +10,8 @@ use crate::{
     strings,
 };
 
-pub async fn get_effective_agent_for_purpose_or_complain<'a>(
+pub async fn get_effective_agent_for_purpose_or_complain(
-    bot: &'a Bot,
+    bot: &Bot,
     message_context: &MessageContext,
     agent_purpose: AgentPurpose,
     response_type: MessageResponseType,