Fix typo, UNKOWN -> UNKNOWN

Found via `typos --hidden --format brief`

Author: kianmeng

sdl3/SDL_pixels.py

@@ -149,7 +149,7 @@ def SDL_ISPIXELFORMAT_ALPHA(format: int) -> bool:
 
 SDL_ColorRange: typing.TypeAlias = SDL_TYPE["SDL_ColorRange", SDL_ENUM]
 
-SDL_COLOR_RANGE_UNKOWN, SDL_COLOR_RANGE_LIMITED, SDL_COLOR_RANGE_FULL = range(3)
+SDL_COLOR_RANGE_UNKNOWN, SDL_COLOR_RANGE_LIMITED, SDL_COLOR_RANGE_FULL = range(3)
 
 SDL_ColorPrimaries: typing.TypeAlias = SDL_TYPE["SDL_ColorPrimaries", SDL_ENUM]