nostr/message/subscription: remove duplicate fmt import

Author: OverOrion

crates/nostr/src/message/subscription.rs

@@ -7,8 +7,6 @@
 #![allow(missing_docs)]
 use core::fmt;
 
-#[cfg(all(feature = "alloc", not(feature = "std")))]
-use alloc::fmt;
 #[cfg(all(feature = "alloc", not(feature = "std")))]
 use alloc::string::{String, ToString};
 #[cfg(all(feature = "alloc", not(feature = "std")))]