build: reduce futures dependencies #316

Job	Run time
check build with madsim	1m 29s
run with single worker thread and deadlock detection	4m 23s
run with address saniziter	4m 18s
cargo manifest check	6s
misc check	5s
rust doc test (ubuntu-latest)	1m 47s
rust ffmt check (ubuntu-latest)	28s
rust machete check	49s
rust doc test (macos-latest)	1m 46s
rust ffmt check (macos-latest)	16s
rust doc test (windows-latest)	2m 12s
rust test with codecov (ubuntu-latest, stable)	4m 19s
rust ffmt check (windows-latest)	1m 24s
rust doc test (ubuntu-24.04-arm)	1m 33s
rust test with codecov (ubuntu-latest, 1.81.0)	4m 3s
rust udeps test (ubuntu-latest)	1m 26s
rust test with codecov (macos-latest, stable)	4m 20s
rust udeps test (macos-latest)	1m 14s
rust ffmt check (ubuntu-24.04-arm)	12s
rust test with codecov (macos-latest, 1.81.0)	3m 9s
rust udeps test (windows-latest)	2m 31s
rust test with codecov (windows-latest, stable)	3m 7s
rust udeps test (ubuntu-24.04-arm)	1m 11s
rust test with codecov (windows-latest, 1.81.0)	3m 45s
rust test with codecov (ubuntu-24.04-arm, stable)	4m 18s
rust test with codecov (ubuntu-24.04-arm, 1.81.0)	4m 11s
	58m 22s

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