Fix variable name

Author: Lynesth

src/MenuStyle.php

@@ -257,7 +257,7 @@ public function setFg($fg, string $fallback = null) : self
     {
         $this->fg = ColourUtil::validateColour(
             $this->terminal,
-            $colour,
+            $fg,
             $fallback
         );
         $this->generateColoursSetCode();
@@ -274,7 +274,7 @@ public function setBg($bg, string $fallback = null) : self
     {
         $this->bg = ColourUtil::validateColour(
             $this->terminal,
-            $colour,
+            $bg,
             $fallback
         );
         $this->generateColoursSetCode();