slabtop: Fix clippy error

error: implicitly cloning a `String` by calling `to_string` on its dereferenced type
   --> src/uu/slabtop/src/parse.rs:296:13
    |
296 |             name.to_string(),
    |             ^^^^^^^^^^^^^^^^ help: consider using: `name.clone()`

src/uu/slabtop/src/parse.rs

@@ -293,7 +293,7 @@ pub(crate) fn parse_data(line: &str) -> Option<(String, Vec<u64>)> {
 
     split.first().map(|name| {
         (
-            name.to_string(),
+            name.clone(),
             split
                 .clone()
                 .into_iter()