remove extra color object from hue shift method

pgfw/extension.py

@@ -340,11 +340,11 @@ def get_busy_channel_count():
 def get_hue_shifted_surface(base, offset):
     surface = base.copy()
     pixels = PixelArray(surface)
-    color = Color(0, 0, 0)
     for x in range(surface.get_width()):
         for y in range(surface.get_height()):
             rgb = surface.unmap_rgb(pixels[x][y])
-            h, s, l, a = Color(*rgb).hsla
+            color = Color(*rgb)
+            h, s, l, a = color.hsla
             if a and surface.get_colorkey() != rgb:
                 color.hsla = (int(h) + offset) % 360, int(s), int(l), int(a)
                 pixels[x][y] = color