fix: clippy

src/main.rs

@@ -59,7 +59,7 @@ impl EventHandler for Handler {
         }
       }
       let bot_channel_message = match bot_channel.is_empty() {
-        true => format!("go to the bot channel"),
+        true => "go to the bot channel".to_string(),
         false => format!("go to https://discord.com/{}/{}", new_member.guild_id, bot_channel),
       };