build(deps): bump tokio from 0.2.21 to 0.2.22

Bumps [tokio](https://github.com/tokio-rs/tokio) from 0.2.21 to 0.2.22.
- [Release notes](https://github.com/tokio-rs/tokio/releases)
- [Commits](https://github.com/tokio-rs/tokio/compare/tokio-0.2.21...tokio-0.2.22)

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

Cargo.lock

@@ -2084,9 +2084,9 @@ checksum = "53953d2d3a5ad81d9f844a32f14ebb121f50b650cd59d0ee2a07cf13c617efed"
 
 [[package]]
 name = "tokio"
-version = "0.2.21"
+version = "0.2.22"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d099fa27b9702bed751524694adbe393e18b36b204da91eb1cbbbbb4a5ee2d58"
+checksum = "5d34ca54d84bf2b5b4d7d31e901a8464f7b60ac145a284fba25ceb801f2ddccd"
 dependencies = [
  "bytes",
  "fnv",