input: Write a python function to find the longest color name from a list of color names.
  assert longest_color_name(['Red', 'Blue', 'Yellow', 'Green', 'Purple', 'Orange']) == 'Yellow'
  assert longest_color_name(['Cyan', 'Magenta', 'Lime', 'Teal', 'Lavender']) == 'Lavender'
  assert longest_color_name(['Black', 'White', 'Pink', 'Gray']) == 'White'
output: def longest_color_name(colors):
      return max(colors, key=len)