Remove once_cell from jwt example #5008

Job	Run time
cargo-hack	9m 3s
check	2m 27s
cargo-deny check (advisories)	10m 27s
cargo-public-api-crates (axum)	56s
cargo-deny check (bans licenses sources)	5m 23s
check-docs	28s
cargo-public-api-crates (axum-core)	38s
cargo-public-api-crates (axum-extra)	1m 0s
dependencies-are-sorted	34s
cargo-public-api-crates (axum-macros)	10m 40s
Spell Check with Typos	5s
test-msrv	12m 28s
test-versions (stable)	2m 28s
test-versions (beta)	13m 58s
test-docs	1m 20s
armv5te-unknown-linux-musleabi	10m 37s
test-nightly	11m 19s
wasm32-unknown-unknown	17s
	1h 34m 8s

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