Chore/update nim version #4120

Job	Run time
coverage	17m 25s
matrix	17s
build / linux-unittest-amd64-v2.0.12	16m 29s
build / linux-contract-amd64-v2.0.12	9m 15s
build / linux-integration-amd64-v2.0.12	1h 11m 33s
build / linux-tools-amd64-v2.0.12	9m 36s
build / macos-unittest-amd64-v2.0.12	22m 7s
build / macos-contract-amd64-v2.0.12	16m 18s
build / macos-integration-amd64-v2.0.12	1h 27m 10s
build / macos-tools-amd64-v2.0.12	18m 56s
build / windows-unittest-amd64-v2.0.12	37m 25s
build / windows-contract-amd64-v2.0.12	22m 43s
build / windows-integration-amd64-v2.0.12	1h 31m 14s
build / windows-tools-amd64-v2.0.12	25m 57s
build / status	1s
	7h 26m 26s

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