chore(deps): update alpine docker tag to v3.21 (kubectl/dockerfile) (#976)

Co-authored-by: IK Renovate Bot <ikbot@renovateapp.com>

Author: ivankatliarchuk

kubectl/Dockerfile

@@ -4,7 +4,7 @@
 # Run:
 # docker run --rm -it kubectl /bin/bash
 ###
-FROM alpine:3.20
+FROM alpine:3.21
 
 # renovate: datasource=github-tags depName=kubernetes/kubectl
 ENV KUBECTL_VERSION=v0.30.2