Fix approval-voting canonicalize off by one #8241

Job	Run time
preflight / preflight	45s
preflight / ci-versions	1m 2s
test-frame-ui	26m 44s
test-full-crypto-feature	2m 30s
cargo-check-benches (master)	20m 22s
cargo-check-benches (current)	21m 56s
cargo-check-all-crate-macos	11m 50s
cargo-check-each-crate (1)	15m 50s
test-node-metrics	10m 15s
cargo-check-each-crate (2)	16m 59s
cargo-check-each-crate (3)	6m 31s
cargo-check-each-crate (4)	15m 15s
cargo-check-each-crate (5)	22m 33s
cargo-check-each-crate (6)	12m 59s
cargo-check-each-crate (7)	25m 32s
test-frame-examples-compile-to-wasm	2m 55s
test-deterministic-wasm	6m 13s
check-tracing	2m 16s
check-metadata-hash	5m 55s
node-bench-regression-guard	12s
All test misc tests passed	1s
	3h 48m 35s

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