third-party/rust: update futures

Summary:
Those newer versions of Futures have compatibility improvements with Tokio,
notably:

- rust-lang/futures-rs#2333
- rust-lang/futures-rs#2358

Reviewed By: farnz

Differential Revision: D26778794

fbshipit-source-id: 5a9dc002083e5edfa5c614d8d2242e586a93fcf6

thrift/lib/rust/src/dep_tests/cargo_thrift/Cargo.toml

@@ -18,7 +18,7 @@ async-trait = "0.1.29"
 codegen_includer_proc_macro = { path = "../../../../../../common/rust/shed/codegen_includer_proc_macro" }
 const-cstr = "0.3.0"
 fbthrift = { path = "../../.." }
-futures = { version = "0.3.5", features = ["async-await", "compat"] }
+futures = { version = "0.3.13", features = ["async-await", "compat"] }
 lazy_static = "1.0"
 ref-cast = "1.0.2"
 serde = { version = "=1.0.118", features = ["derive", "rc"] }