feature: Support for dereference links -L follow

du has -L flag which allows it to dereference or follow
symlinks. Clone this feature into dust.
https://github.com/bootandy/dust/issues/276

src/platform.rs

@@ -21,9 +21,7 @@ pub fn get_metadata(d: &Path, use_apparent_size: bool) -> Option<(u64, Option<(u
                 Some((md.blocks() * get_block_size(), Some((md.ino(), md.dev()))))
             }
         }
-        Err(_e) => {
-            None
-        }
+        Err(_e) => None,
     }
 }