Bump futures-io from 0.3.5 to 0.3.8

Bumps [futures-io](https://github.com/rust-lang/futures-rs) from 0.3.5 to 0.3.8.
- [Release notes](https://github.com/rust-lang/futures-rs/releases)
- [Changelog](https://github.com/rust-lang/futures-rs/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rust-lang/futures-rs/compare/0.3.5...0.3.8)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Cargo.lock

@@ -1774,9 +1774,9 @@ dependencies = [
 
 [[package]]
 name = "futures-io"
-version = "0.3.5"
+version = "0.3.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "de27142b013a8e869c14957e6d2edeef89e97c289e69d042ee3a49acd8b51789"
+checksum = "611834ce18aaa1bd13c4b374f5d653e1027cf99b6b502584ff8c9a64413b30bb"
 
 [[package]]
 name = "futures-macro"