Update kube requirement from 0.20 to 0.22

Updates the requirements on [kube](https://github.com/clux/kube-rs) to permit the latest version.
- [Release notes](https://github.com/clux/kube-rs/releases)
- [Changelog](https://github.com/clux/kube-rs/blob/master/CHANGELOG.md)
- [Commits](kube-rs/kube@0.20.0...0.22.1)

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

Cargo.toml

@@ -41,7 +41,7 @@ docopt = "1.0"
 either = "1.5"
 futures = "0.3"
 k8s-openapi = { version = "0.6", default-features = false, features = ["v1_15"], optional = true }
-kube = { version = "0.20", features = ["openapi"], optional = true }
+kube = { version = "0.22", features = ["openapi"], optional = true }
 log = "0.4"
 notifier = { version = "0.1", features = ["tcp_typed"] }
 once_cell = "1.0"