Fix Rust beta compiler errors (1.77) #15213

Job	Run time
target-branch-check	1s
release-tests-windows	22m 56s
beacon-chain-tests	17m 45s
cargo-udeps	7m 12s
check-code	7m 45s
check-msrv	4m 31s
cli-check	8m 29s
compile-with-beta-compiler	13m 13s
debug-tests-ubuntu	13m 40s
dockerfile-ubuntu	14m 0s
doppelganger-protection-test	20m 44s
ef-tests-ubuntu	13m 54s
eth1-simulator-ubuntu	20m 24s
execution-engine-integration-ubuntu	14m 54s
merge-transition-ubuntu	20m 11s
network-tests	8m 6s
no-eth1-simulator-ubuntu	18m 28s
op-pool-tests	11m 0s
release-tests-ubuntu	19m 37s
slasher-tests	1m 7s
state-transition-vectors-ubuntu	2m 21s
syncing-simulator-ubuntu	12m 28s
test-suite-success	7s
	4h 32m 53s

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