Add the "Pale Flat World" to the flat world preset options in the game

Minecraft currently offers 9 flat world presets. The Pale Garden biome features dark grass and a gray sky, even in dry weather. A "Pale Flat World" preset should be added that mirrors the Pale Garden's color palette; it would consist of a bottom layer of Bedrock, 59 layers of stone, 3 layers of dirt, and a top layer of grass, along with a gray sky.