Bump metadata version to 5 #647

Job	Run time
set-image	1s
fmt	2m 44s
clippy-examples (STD)	10m 34s
clippy	9m 51s
clippy-examples (WASM)	3m 55s
spellcheck	1m 27s
check (STD)	7m 46s
check (WASM)	1m 59s
dylint	4m 52s
check (RISCV)	1m 54s
build (STD)	13m 23s
test	18m 15s
build (WASM)	1m 48s
examples-test	35m 45s
docs	8m 17s
codecov	16m 47s
examples-contract-build (WASM)	17m 37s
examples-contract-build (RISCV)	3m 19s
examples-docs	4m 38s
fuzz	0s
measurements / contract-sizes	26m 41s
	3h 11m 33s

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