Bump async-std from 1.6.3 to 1.6.4

Bumps [async-std](https://github.com/async-rs/async-std) from 1.6.3 to 1.6.4.
- [Release notes](https://github.com/async-rs/async-std/releases)
- [Changelog](https://github.com/async-rs/async-std/blob/master/CHANGELOG.md)
- [Commits](https://github.com/async-rs/async-std/compare/v1.6.3...v1.6.4)

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

crates/async-std-resolver/Cargo.toml

@@ -64,11 +64,11 @@ name = "async_std_resolver"
 path = "src/lib.rs"
 
 [dependencies]
-async-std = "1.0"
+async-std = "1.6"
 async-trait = "0.1.36"
 futures = { version = "0.3.5", default-features = false, features = ["std"] }
 trust-dns-resolver = { version = "0.20.0-alpha.2", path = "../resolver", default-features = false }
 
 [dev-dependencies]
-async-std = { version = "1.0", features = ["attributes"] }
+async-std = { version = "1.6", features = ["attributes"] }
 trust-dns-resolver = { version = "0.20.0-alpha.2", path = "../resolver", default-features = false, features = ["testing"] }