Make compatible with Kubernetes v1.22

CHANGELOG.adoc

@@ -3,10 +3,14 @@
 == 0.6.0 - unreleased
 
 :262: https://github.com/stackabletech/agent/pull/262[#262]
+:267: https://github.com/stackabletech/agent/pull/267[#267]
 
 === Changed
 * Lazy validation of repository URLs changed to eager validation
   ({262}).
+* `certificates.k8s.io/v1` used instead of `certificates.k8s.io/v1beta1`
+  so that the Stackable Agent is now compatible with Kubernetes v1.22
+  but not any longer with versions prior to v1.19 ({267}).
 
 == 0.5.0 - 2021-07-26
 

Cargo.toml

@@ -19,7 +19,7 @@ flate2 = "1.0"
 futures-util = "0.3"
 handlebars = "4.1"
 hostname = "0.3"
-k8s-openapi = { version = "0.11", default-features = false, features = ["api", "v1_18"] }
+k8s-openapi = { version = "0.11", default-features = false, features = ["api", "v1_20"] }
 krator = { git = "https://github.com/stackabletech/krustlet.git", branch = "stackable_patches_v0.7.0" } # version = "0.2"
 kube = { version= "0.48", default-features = false, features = ["derive", "native-tls"] }
 kubelet = { git = "https://github.com/stackabletech/krustlet.git", branch = "stackable_patches_v0.7.0", default-features = true, features= ["derive", "cli"] } # version = "0.7"

docs/modules/ROOT/pages/limitations.adoc

@@ -2,5 +2,6 @@
 
 The Stackable Agent has limitations, some of which are documented here.
 
+* Kubernetes v1.19+ is required.
 * The maximum number of pods supported by the agent is currently hardcoded to 110.
   This restriction can be lifted if the need arises.