Format all source files

cargo-fmt skips files because of rust-lang/rustfmt#3253

Author: Luminiscental

src/day12.rs

@@ -1,6 +1,6 @@
 use crate::day::Day;
-use itertools::Itertools;
 use hashbrown::HashMap;
+use itertools::Itertools;
 
 type Cave = [u8; 2];
 

src/day13.rs

@@ -1,10 +1,7 @@
 use crate::{day::Day, util::CollectArray};
-use itertools::Itertools;
-use std::{
-    collections::VecDeque,
-    mem,
-};
 use hashbrown::HashSet;
+use itertools::Itertools;
+use std::{collections::VecDeque, mem};
 
 fn fold(grid: &mut HashSet<[u16; 2]>, fold: (u8, u16)) {
     *grid = mem::take(grid)