Fix color constants

No idea how I replaced yellow with brown, but somehow I messed that
up. Whatever, I wrote that code a month and a half ago lol

src/io.rs

@@ -44,14 +44,14 @@ pub fn quit() -> ! {
 /// The colors on a terminal.
 #[allow(unused)]
 pub enum Color {
-    Black = 0,
-    Red = 1,
-    Green = 2,
-    Brown = 3,
-    Blue = 4,
-    Magenta = 5,
-    Cyan = 6,
-    White = 7,
+    Black = pancurses::COLOR_BLACK as _,
+    Red = pancurses::COLOR_RED as _,
+    Green = pancurses::COLOR_GREEN as _,
+    Yellow = pancurses::COLOR_YELLOW as _,
+    Blue = pancurses::COLOR_BLUE as _,
+    Magenta = pancurses::COLOR_MAGENTA as _,
+    Cyan = pancurses::COLOR_CYAN as _,
+    White = pancurses::COLOR_WHITE as _,
 }
 
 #[derive(Error, Debug)]

src/level.rs

@@ -106,7 +106,7 @@ impl DungeonLevel {
             win.mv(y as _, 0);
             for x in 0..LEVEL_SIZE.0 {
                 if (x + y) % 2 == 0 {
-                    set_color(win, Color::Cyan);
+                    set_color(win, Color::Yellow);
                 } else {
                     set_color(win, Color::Red);
                 }