ci: bump actions/cache from 4 to 5 (#2130) #2983

Job	Run time
test (1.85.0)	24s
test (stable)	20s
build (1.85.0, thumbv7em-none-eabi)	23s
build (stable, wasm32-unknown-unknown)	19s
build (1.85.0, wasm32-unknown-unknown)	22s
build (stable, thumbv7em-none-eabi)	22s
minimal-versions	0s
	2m 10s

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