[CodeHealth][rust] Update futures 0.3.27 => 0.3.31

This PR updates the `futures` crate to `0.3.31`. This crate was causing
audit failures on a different PR updating `chrono`.

This change removes the previous `extra_src_roots` instructions for the
future deps, as those started panicking when running `gnrt` in the
current version.

`chrono` PR: #27693

Resolves brave/brave-browser#44057

third_party/rust/chromium_crates_io/gnrt_config.toml

@@ -190,22 +190,6 @@ license_files = ['../../../../../common/licenses/Apache-2.0']
 [crate.funty]
 license_files = ['LICENSE.txt']
 
-[crate.futures-channel]
-extra_src_roots = [ "../no_atomic_cas.rs" ]
-extra_build_script_src_roots = [ "../no_atomic_cas.rs" ]
-
-[crate.futures-core]
-extra_src_roots = [ "../no_atomic_cas.rs" ]
-extra_build_script_src_roots = [ "../no_atomic_cas.rs" ]
-
-[crate.futures-task]
-extra_src_roots = [ "../no_atomic_cas.rs" ]
-extra_build_script_src_roots = [ "../no_atomic_cas.rs" ]
-
-[crate.futures-util]
-extra_src_roots = [ "../no_atomic_cas.rs" ]
-extra_build_script_src_roots = [ "../no_atomic_cas.rs" ]
-
 [crate.fvm_ipld_blockstore]
 license_files = ['../../../../../common/licenses/Apache-2.0']