fix nightly clippy warning

src/write.rs

@@ -790,7 +790,7 @@ impl<W: Write + io::Seek> Drop for ZipWriter<W> {
     fn drop(&mut self) {
         if !self.inner.is_closed() {
             if let Err(e) = self.finalize() {
-                let _ = write!(&mut io::stderr(), "ZipWriter drop failed: {:?}", e);
+                let _ = write!(io::stderr(), "ZipWriter drop failed: {:?}", e);
             }
         }
     }