Update ECOSYSTEM.md to include `tower-sessions` #3967

Job	Run time
check-docs	37s
check	1m 41s
cargo-public-api-crates (axum)	1m 7s
cargo-hack	10m 33s
cargo-public-api-crates (axum-core)	50s
cargo-deny check (advisories)	24s
cargo-public-api-crates (axum-extra)	1m 44s
dependencies-are-sorted	19s
cargo-deny check (bans licenses sources)	24s
cargo-public-api-crates (axum-macros)	1m 6s
Spell Check with Typos	4s
test-nightly	2m 58s
armv5te-unknown-linux-musleabi	49s
test-docs	2m 2s
test-msrv	12m 25s
test-versions (stable)	3m 9s
wasm32-unknown-unknown	18s
test-versions (beta)	3m 16s
	43m 46s

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