feat: add test case list to day template

src/bin/create_day.rs

@@ -10,7 +10,7 @@ fn parse(s: &str) -> Result<Input> {
     Ok(())
 }
 
-#[aoc(day = {{ day }}, parse = parse)]
+#[aoc(day = {{ day }}, parse = parse, test_cases = ["day_{{ day }}.txt"])]
 fn day_{{ day }}(mut input: Input) -> Result<()> {
     // Part 1
     println!("Part one: ");