rm: Remove unused import and improve code readability

- Eliminated unnecessary `PathBuf` import in `features/fsext.rs`.
- Replaced `unwrap_or(PathBuf::new())` with the more idiomatic `unwrap_or_default()`.

Author: shskwmt

src/uucore/src/lib/features/fsext.rs

@@ -28,9 +28,6 @@ static EXIT_ERR: i32 = 1;
 #[cfg(windows)]
 use crate::show_warning;
 
-#[cfg(windows)]
-use std::path::PathBuf;
-
 #[cfg(windows)]
 use std::ffi::OsStr;
 #[cfg(windows)]
@@ -265,7 +262,7 @@ impl MountInfo {
 
         let mount_dir = Path::new(&mount_root)
             .canonicalize()
-            .unwrap_or(PathBuf::new())
+            .unwrap_or_default()
             .to_str()
             .unwrap()
             .to_string();