chore(ci): prevent msrv checks from blocking PRs #4241

Job	Run time
build-nargo	2m 8s
build-noirc-abi	2m 32s
build-noir-wasm	4m 25s
build-acvm-js	2m 54s
noir-js-backend-barretenberg	47s
noirc_abi	42s
ACVM JS (Browser)	1m 30s
noir_codegen	58s
Noir JS	1m 32s
ACVM JS (Node.js)	35s
noir_wasm	1m 4s
Integration Tests (Node)	5m 39s
Integration Tests (Browser)	5m 18s
End	1s
	30m 5s

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