Remove redundant borrow in Last.fm format! argument

Fixes clippy::useless_borrows_in_formatting, new in Rust 1.99, which
failed the CI check job.

shanty-data/src/lastfm.rs

@@ -29,7 +29,7 @@ impl ArtistBioFetcher for LastFmBioFetcher {
         let url = format!(
             "https://ws.audioscrobbler.com/2.0/?method=artist.getinfo&artist={}&api_key={}&format=json",
             urlencoded(&artist_info.name),
-            &self.api_key,
+            self.api_key,
         );
 
         let resp = match self.client.get(&url).send().await {