chore(console): update to clap v3 stable (#247)

This branch updates the `tokio-console` CLI's `clap` dependency from
3.0.0-beta.5 to the new stable release of `clap` 3.0. Nothing important
seems to have changed between beta.5 and the stable release, but it's
nice to get off the beta.

Author: hawkw

Cargo.lock

@@ -28,7 +28,7 @@ keywords = [
 [dependencies]
 atty = "0.2"
 console-api = { version = "0.1.0", path = "../console-api", features = ["transport"] }
-clap = { version = "3.0.0-beta.5", features = ["cargo", "derive", "env"] }
+clap = { version = "3", features = ["cargo", "derive", "env"] }
 tokio = { version = "1", features = ["full", "rt-multi-thread"] }
 tonic = { version = "0.6", features = ["transport"] }
 futures = "0.3"