Apply more recent/nightly clippy lints (#7916)

# Description

- Use inline format strings in dataframe code
- Fix manual `.is_ascii_digit()` check
- Remove unnecessary `.into_iter()` calls

crates/nu-command/src/filesystem/ls.rs

@@ -178,7 +178,6 @@ impl Command for Ls {
         let mut hidden_dirs = vec![];
 
         Ok(paths_peek
-            .into_iter()
             .filter_map(move |x| match x {
                 Ok(path) => {
                     let metadata = match std::fs::symlink_metadata(&path) {