Update graceful shutdown example #4071

Job	Run time
check	39s
check-docs	20s
cargo-hack	2m 56s
cargo-public-api-crates (axum)	31s
cargo-public-api-crates (axum-core)	25s
cargo-deny check (advisories)	21s
cargo-public-api-crates (axum-extra)	28s
dependencies-are-sorted	18s
Spell Check with Typos	6s
cargo-deny check (bans licenses sources)	25s
cargo-public-api-crates (axum-macros)	14s
test-nightly	1m 45s
test-docs	1m 47s
wasm32-unknown-unknown	20s
test-versions (stable)	1m 56s
armv5te-unknown-linux-musleabi	27s
test-msrv	1m 17s
test-versions (beta)	1m 57s
	16m 12s

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