refactor: apply clippy hints

src/parse.rs

@@ -78,14 +78,11 @@ fn nodes_from_str(s: &str) -> Result<Vec<Node>, Error> {
     let mut nodes = Vec::new();
     let mut state = ParsingState::default();
 
-    let is_ignored_char = |c: &char| match c {
-        ' ' | '&' => false,
-        _ => true,
-    };
+    let is_ignored_char = |c: &char| !matches!(c, ' ' | '&');
 
     let filtered_string: String = s.chars().filter(is_ignored_char).collect();
 
-    for (i, c) in filtered_string.chars().enumerate() {
+    for (i, c) in filtered_string.char_indices() {
         let mut start = false;
         match state {
             ParsingState::Start => start = true,