chore: update Rust version in CI configuration to 1.78.0 #560

Job	Run time
Build Libretro (1.74.0)	1m 26s
Build (1.74.0)	4m 57s
Build Libretro (1.75.0)	1m 24s
Build (1.75.0)	4m 55s
Build Libretro (1.76.0)	1m 24s
Build Libretro Android (1.74.0)	3m 1s
Build (1.76.0)	4m 49s
Build Libretro (1.77.0)	1m 21s
Build Libretro Android (1.75.0)	3m 0s
Build (1.77.0)	4m 49s
Build SDL (1.74.0)	22s
Build (1.78.0)	4m 48s
Build Libretro (1.78.0)	1m 25s
Build SDL (1.75.0)	12s
Build Libretro (1.79.0)	1m 23s
Build (1.79.0)	4m 42s
Build SDL (1.76.0)	12s
Build Libretro Android (1.76.0)	2m 59s
Build Libretro (1.80.0)	1m 24s
Build SDL (1.77.0)	1s
Build (1.80.0)	4m 48s
Build Libretro Android (1.77.0)	2m 52s
Build Libretro (latest)	1m 19s
Build SDL (1.78.0)	1s
Build Libretro Android (1.78.0)	2m 51s
Build (latest)	4m 32s
Build SDL (1.79.0)	1s
Build Libretro Android (1.79.0)	2m 55s
Build SDL (1.80.0)	1s
Build Libretro Android (1.80.0)	2m 56s
Build Simple (1.74.0)	1m 19s
Build SDL (latest)	1s
Build Libretro Android (latest)	2m 56s
Build Simple (1.75.0)	1m 16s
Build Simple (1.76.0)	1m 14s
Build WASM (1.78.0, 18)	3m 48s
Build Simple (1.77.0)	1m 11s
Build WASM (1.79.0, 18)	3m 52s
Build Simple (1.78.0)	1m 13s
Build WASM (1.80.0, 18)	3m 37s
Build Simple (1.79.0)	1m 14s
Build Simple (1.80.0)	1m 14s
Build WASM (1.82.0, 18)	3m 45s
Build WASM (latest, 18)	3m 41s
Build Simple (latest)	1m 2s
	1h 42m 13s

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