Update scripts/deps libpng to 1.6.47, SDL2 to 2.32.0, enable SDL3. #951

Job	Run time
AArch64-Switch	1m 36s
ARM-3DS	1m 13s
ARM-NDS	29s
AddressSanitizer	1m 48s
ARM-NDS-BlocksDS	39s
darwin-arm64	48s
darwin-x86_64	1m 0s
Emscripten-HTML5	2m 16s
MemorySanitizer	1m 18s
MSYS2-MINGW32	2m 18s
MSYS2-MINGW64	2m 19s
PowerPC-Wii	1m 18s
PowerPC-WiiU	1m 32s
UndefinedBehaviorSanitizer	1m 3s
unix	1m 11s
unix-misc	2m 59s
unix-portable	1m 6s
Vita	1m 36s
	26m 29s

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