Upgrade env to v20.0.0-rc2 #3366

Job	Run time
check-git-rev-deps	16s
build-fuzz	2m 44s
cargo-deny (advisories)	5m 3s
build-and-test (ubuntu-latest, x86_64-unknown-linux-gnu)	7m 42s
cargo-deny (bans licenses sources)	4m 27s
build-and-test (ubuntu-latest, aarch64-unknown-linux-gnu, true)	4m 7s
docs	5m 17s
fmt	11s
build-and-test (macos-latest, x86_64-apple-darwin)	24m 6s
publish-dry-run	0s
rust-analyzer-compat	9m 33s
build-and-test (macos-latest, aarch64-apple-darwin)	18m 25s
build-and-test (windows-latest, x86_64-pc-windows-msvc)	26m 55s
complete	1s
	1h 48m 47s

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