Update dependency metallb/frr-k8s to v0.0.21

Signed-off-by: red-hat-konflux <126015336+red-hat-konflux[bot]@users.noreply.github.com>

Author: red-hat-konflux[bot]

clab/kind/frr-k8s/kustomization.yaml

@@ -1,5 +1,5 @@
 resources:
-- https://github.com/metallb/frr-k8s/config/default/?timeout=120&ref=v0.0.18
+- https://github.com/metallb/frr-k8s/config/default/?timeout=120&ref=v0.0.21
 patches:
 - path: loglevel-patch.yaml
   target: