feat!: upgrade flux components to v0.18.0 (#96)

Co-authored-by: onedr0p <onedr0p@users.noreply.github.com>

tmpl/cluster/gotk-sync.yaml

@@ -10,7 +10,7 @@ spec:
     branch: main
   url: ${BOOTSTRAP_GIT_REPOSITORY}
 ---
-apiVersion: kustomize.toolkit.fluxcd.io/v1beta1
+apiVersion: kustomize.toolkit.fluxcd.io/v1beta2
 kind: Kustomization
 metadata:
   name: flux-system
@@ -22,7 +22,6 @@ spec:
   sourceRef:
     kind: GitRepository
     name: flux-system
-  validation: client
   decryption:
     provider: sops
     secretRef: