fix: retrieve metadata for symbolic links without following them

Previously, the function get_metadata in platform.rs used `fs::metadata` which follows symbolic links
and returns metadata for the target file. This caused issues #421: du / dust disagreement
when trying to determine properties of the symbolic link itself

src/main.rs

@@ -228,7 +228,7 @@ fn main() {
     let follow_links = options.get_flag("dereference_links");
 
     let allowed_filesystems = limit_filesystem
-        .then(|| get_filesystem_devices(&target_dirs))
+        .then(|| get_filesystem_devices(&target_dirs, follow_links))
         .unwrap_or_default();
     let simplified_dirs = simplify_dir_names(&target_dirs);