ci: Bump k8s version and update compatability matrix

.github/workflows/ci.yaml

@@ -63,8 +63,8 @@ jobs:
     strategy:
       matrix:
         kind-image:
-          - 'kindest/node:v1.21.1'
-          - 'kindest/node:v1.22.0'
+          - 'kindest/node:v1.23.0'
+          - 'kindest/node:v1.22.4'
     steps:
     - uses: actions/checkout@v2
       with:

README.md

@@ -91,13 +91,13 @@ $ minikube addons disable metrics-server
 
 The following versions are supported and work as we test against these versions in their respective branches. But note that other versions might work!
 
-| kube-prometheus stack                                                                    | Kubernetes 1.18 | Kubernetes 1.19 | Kubernetes 1.20 | Kubernetes 1.21 | Kubernetes 1.22 |
-|------------------------------------------------------------------------------------------|-----------------|-----------------|-----------------|-----------------|-----------------|
-| [`release-0.6`](https://github.com/prometheus-operator/kube-prometheus/tree/release-0.6) | ✗               | ✔               | ✗               | ✗               | ✗               |
-| [`release-0.7`](https://github.com/prometheus-operator/kube-prometheus/tree/release-0.7) | ✗               | ✔               | ✔               | ✗               | ✗               |
-| [`release-0.8`](https://github.com/prometheus-operator/kube-prometheus/tree/release-0.8) | ✗               | ✗               | ✔               | ✔               | ✗               |
-| [`release-0.9`](https://github.com/prometheus-operator/kube-prometheus/tree/release-0.9) | ✗               | ✗               | ✗               | ✔               | ✔               |
-| [`main`](https://github.com/prometheus-operator/kube-prometheus/tree/main)               | ✗               | ✗               | ✗               | ✔               | ✔               |
+| kube-prometheus stack                                                                      | Kubernetes 1.18 | Kubernetes 1.19 | Kubernetes 1.20 | Kubernetes 1.21 | Kubernetes 1.22 | Kubernetes 1.23 |
+|--------------------------------------------------------------------------------------------|-----------------|-----------------|-----------------|-----------------|-----------------|-----------------|
+| [`release-0.6`](https://github.com/prometheus-operator/kube-prometheus/tree/release-0.6)   | ✗               | ✔               | ✗               | ✗               | ✗               | ✗               |
+| [`release-0.7`](https://github.com/prometheus-operator/kube-prometheus/tree/release-0.7)   | ✗               | ✔               | ✔               | ✗               | ✗               | ✗               |
+| [`release-0.8`](https://github.com/prometheus-operator/kube-prometheus/tree/release-0.8)   | ✗               | ✗               | ✔               | ✔               | ✗               | ✗               |
+| [`release-0.9`](https://github.com/prometheus-operator/kube-prometheus/tree/release-0.9)   | ✗               | ✗               | ✗               | ✔               | ✔               | ✗               |
+| [`main`](https://github.com/prometheus-operator/kube-prometheus/tree/main)                 | ✗               | ✗               | ✗               | ✗               | ✔               | ✔               |
 
 ## Quickstart