fix: back to forbid `unsafe` #4092

Job	Run time
check	55s
cargo-public-api-crates (axum)	1m 0s
check-docs	26s
cargo-hack	3m 15s
cargo-public-api-crates (axum-core)	50s
cargo-deny check (advisories)	26s
cargo-public-api-crates (axum-extra)	1m 1s
dependencies-are-sorted	19s
Spell Check with Typos	5s
cargo-deny check (bans licenses sources)	23s
cargo-public-api-crates (axum-macros)	49s
test-msrv	7m 15s
armv5te-unknown-linux-musleabi	30s
test-nightly	1m 48s
test-docs	1m 35s
test-versions (stable)	2m 2s
test-versions (beta)	2m 0s
wasm32-unknown-unknown	26s
	25m 5s

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