feat(scaffold): change default return type to Option<usize>

utils/scaffold/src/main.rs

@@ -8,11 +8,11 @@ use std::{
     process,
 };
 
-const MODULE_TEMPLATE: &str = r#"pub fn part_one(input: &str) -> Option<u32> {
+const MODULE_TEMPLATE: &str = r#"pub fn part_one(input: &str) -> Option<usize> {
     None
 }
 
-pub fn part_two(input: &str) -> Option<u32> {
+pub fn part_two(input: &str) -> Option<usize> {
     None
 }