fix: fix clippy

Author: vivianjeng

src/utils.rs

@@ -47,7 +47,7 @@ pub fn download_zkey(depth: u16) -> Result<String, Box<dyn Error>> {
     let out_dir = std::env::temp_dir();
     let dest_path = out_dir.join(dest_filename.clone());
     if !dest_path.exists() {
-        let url = format!("{}{}", base_url, filename);
+        let url = format!("{base_url}{filename}");
         let client = Client::new();
         let mut resp = client.get(&url).send()?.error_for_status()?;
         let mut out = File::create(&dest_path)?;