kep-2305: bump latest-milestone to v1.29

Same change for beta milestone as well.

Signed-off-by: Pranshu Srivastava <[email protected]>

Author: rexagod

keps/sig-instrumentation/2305-metrics-cardinality-enforcement/kep.yaml

@@ -19,7 +19,7 @@ creation-date: 2020-04-15
 last-updated: 2023-05-28
 stage: beta
 status: implementable
-latest-milestone: "v1.28"
+latest-milestone: "v1.29"
 milestone:
-  beta: "v1.28"
+  beta: "v1.29"
 disable-supported: true