keyfork wizard: upcast i and index to avoid wrapping add

crates/keyfork/src/cli/wizard.rs

@@ -132,8 +132,8 @@ fn generate_shard_secret(
         for i in 0..keys_per_shard {
             pm.prompt_message(Message::Text(format!(
                 "Please remove all keys and insert key #{} for user #{}",
-                i + 1,
-                index + 1,
+                (i as u16) + 1,
+                (index as u16) + 1,
             )))?;
             let card_backend = loop {
                 if let Some(c) = PcscBackend::cards(None)?.next().transpose()? {