Red mooshrooms use 1.14 texture when using the Programmer Art resource pack

In 1.21.5, the models of cows and mooshrooms were changed. In that version, temperate cows and red mooshrooms incorrectly used their 1.14 texture when the Programmer Art pack was enabled. Temperate cows were fixed in 1.21.6 to use their 1.13 texture (see MC-280047), but not red mooshrooms.