Board: use place for random board not place_unchecked

src/repr/board.rs

@@ -172,7 +172,7 @@ impl Board {
         let mut rng = rand::rng();
         for _ in 0..steps {
             if let Some(m) = new.possible_moves(p).choose(&mut rng) {
-                new.place_unchecked(m, p);
+                let _ = new.place(m, p);
             }
 
             p = !p;