For pawn caputre rays do same as knight rays

rs/src/board.rs

@@ -196,18 +196,13 @@ impl PieceType {
             Color::Black => Dir::Down,
             Color::White => Dir::Up,
         };
-        let mut capture_rays = vec![];
-        if let Some(p) = position.chain(&[&direction, &Dir::Left]) {
-            capture_rays.push(Ray {
+        [&[&direction, &Dir::Left], &[&direction, &Dir::Right]]
+            .into_iter()
+            .filter_map(|dirs| position.chain(dirs))
+            .map(|p| Ray {
                 positions: vec![p],
-            });
-        }
-        if let Some(p) = position.chain(&[&direction, &Dir::Right]) {
-            capture_rays.push(Ray {
-                positions: vec![p],
-            });
-        }
-        capture_rays
+            })
+            .collect()
     }
 
     // Knight