Fix std::write benchmark

benches/src/std_write.rs

@@ -22,6 +22,7 @@ pub fn big_table(b: &mut criterion::Bencher<'_>, size: &usize) {
             write!(&mut output, "</tr>\n").unwrap();
         }
         write!(&mut output, "</table>").unwrap();
+        output
     });
 }
 
@@ -80,6 +81,7 @@ pub fn teams(b: &mut criterion::Bencher<'_>, _: &usize) {
             </html>"
         )
         .unwrap();
+        output
     });
 }