Update the latest milestone.

Author: cici37

keps/sig-api-machinery/3488-cel-admission-control/kep.yaml

@@ -38,7 +38,7 @@ stage: beta
 # 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: "v1.28"
+latest-milestone: "v1.29"
 
 # The milestone at which this feature was, or is targeted to be, at each stage.
 milestone: