mark 4369 as implemented:

Author: SergeyKanzhelev

keps/sig-node/4369-allow-special-characters-environment-variable/kep.yaml

@@ -5,7 +5,7 @@ authors:
 owning-sig: sig-node
 participating-sigs:
   - sig-api-machinery
-status: implementable
+status: implemented
 creation-date: 2023-12-21
 reviewers:
   - "@liggitt"