[board] Implement Display for Color

board/src/piece.rs

@@ -38,6 +38,19 @@ impl Default for Color {
     }
 }
 
+impl fmt::Display for Color {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(
+            f,
+            "{}",
+            match self {
+                Color::White => "White",
+                Color::Black => "Black",
+            },
+        )
+    }
+}
+
 impl TryFrom<char> for Color {
     type Error = TryFromError;