Update low-level-rustls example - added http2 feature flag #5274

Job	Run time
check-docs	24s
check	2m 15s
cargo-public-api-crates (axum)	52s
cargo-hack	2m 53s
cargo-public-api-crates (axum-core)	40s
cargo-deny check (advisories)	27s
dependencies-are-sorted	32s
cargo-public-api-crates (axum-extra)	50s
cargo-deny check (bans licenses sources)	24s
Spell Check with Typos	7s
cargo-public-api-crates (axum-macros)	38s
test-versions (stable)	1m 17s
test-msrv	2m 47s
test-versions (beta)	3m 55s
armv5te-unknown-linux-musleabi	30s
test-docs	1m 31s
test-nightly	1m 25s
wasm32-unknown-unknown	21s
	21m 48s

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