added multipath function

Author: AmosOO7

src/descriptor_handler.rs

@@ -84,7 +84,9 @@ pub fn generate_multipath_descriptor(
 ) -> Result<Value> {
     // Only BIP84 supported in this example
     if script_type != 84 {
-        return Err(anyhow!("Only BIP84 is supported for multipath at the moment."));
+        return Err(anyhow!(
+            "Only BIP84 is supported for multipath at the moment."
+        ));
     }
 
     #[allow(deprecated)]