chore(deps): update kindest/node docker tag to v1.28.6

| datasource | package      | from    | to      |
| ---------- | ------------ | ------- | ------- |
| docker     | kindest/node | v1.28.0 | v1.28.6 |

.github/workflows/ci.yaml

@@ -86,7 +86,7 @@ jobs:
           # from https://hub.docker.com/r/kindest/node/tags
           - v1.26.13 # renovate: kindest
           - v1.27.10 # renovate: kindest
-          - v1.28.0 # renovate: kindest
+          - v1.28.6 # renovate: kindest
           - v1.29.1 # renovate: kindest
     steps:
       - name: Checkout