Make futures crate optional in solana-type-overrides #6213

Job	Run time
cargo-test-sbf (token/program)	9m 59s
check	3m 18s
cargo-test-sbf (instruction-padding/program, token/program-2022, token/program-2022-test)	13m 28s
test (token/cli, token/program, token/program-2022, associated-token-account/program, instruction...	16m 16s
cargo-test-sbf (associated-token-account/program, associated-token-account/program-test)	11m 45s
test (single-pool/cli, single-pool/program)	19m 31s
cargo-test-sbf (token-upgrade/program)	10m 19s
cargo-test-sbf (feature-proposal/program)	9m 52s
test (token-upgrade/cli, token-upgrade/program)	14m 49s
cargo-test-sbf (governance/addin-mock/program, governance/program)	14m 14s
cargo-test-sbf (memo/program)	9m 34s
cargo-test-sbf (name-service/program)	8m 55s
cargo-test-sbf (stake-pool/program)	14m 3s
cargo-test-sbf (single-pool/program)	9m 14s
	2h 45m 17s

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