add Default impl to AocRunner

libaoc/src/lib.rs

@@ -18,13 +18,14 @@ pub struct Day {
     pub part2: Option<fn() -> miette::Result<()>>,
 }
 
+#[derive(Default)]
 pub struct AocRunner {
     days: Vec<Day>,
 }
 
 impl AocRunner {
     pub fn new() -> Self {
-        Self { days: vec![] }
+        Self::default()
     }
 
     pub fn day(&mut self, day: Day) -> &mut Self {