Promote to stable

Author: cici37

keps/sig-api-machinery/2876-crd-validation-expression-language/kep.yaml

@@ -22,17 +22,18 @@ see-also:
   - "/keps/sig-api-machinery/95-custom-resource-definitions"
 
 # The target maturity stage in the current dev cycle for this KEP.
-stage: beta
+stage: stable
 
 # The most recent milestone for which work toward delivery of this KEP has been
 # done. This can be the current (upcoming) milestone, if it is being actively
 # worked on.
-latest-milestone: "v1.27"
+latest-milestone: "v1.28"
 
 # The milestone at which this feature was, or is targeted to be, at each stage.
 milestone:
   alpha: "v1.23"
   beta:  "v1.25"
+  stable: "v1.28"
 
 # The following PRR answers are required at alpha release
 # List the feature gate name and the components for which it must be enabled