Update milestone to 1.28 for KEP 3157

Author: p0lyn0mial

keps/sig-api-machinery/3157-watch-list/kep.yaml

@@ -20,7 +20,7 @@ stage: alpha
 # 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: