fixed cargo fmt issue

src/data.rs

@@ -60,7 +60,7 @@ impl Value {
                     v.push(format!("{}:{}", json!(key), value.to_json()?));
                 }
                 Ok(format!("{{{}}}", v.join(",")))
-            },
+            }
             _ => err!(CESRError::Conversion("cannot convert to string".to_string())),
         }
     }