Use a Vec for the name col padding

src/dev/check.rs

@@ -14,9 +14,11 @@ use crate::{
     collections::{hash_set_with_capacity, HashSet},
     exercise::{RunnableExercise, OUTPUT_CAPACITY},
     info_file::{ExerciseInfo, InfoFile},
-    CURRENT_FORMAT_VERSION, MAX_EXERCISE_NAME_LEN,
+    CURRENT_FORMAT_VERSION,
 };
 
+const MAX_EXERCISE_NAME_LEN: usize = 32;
+
 // Find a char that isn't allowed in the exercise's `name` or `dir`.
 fn forbidden_char(input: &str) -> Option<char> {
     input.chars().find(|c| !c.is_alphanumeric() && *c != '_')