fix(bootstrap): Add missing coredns repo (#1491)

bootstrap/templates/kubernetes/bootstrap/talos/helmfile.yaml.j2

@@ -2,6 +2,8 @@
 repositories:
   - name: cilium
     url: https://helm.cilium.io
+  - name: coredns
+    url: https://coredns.github.io/helm
   - name: postfinance
     url: https://postfinance.github.io/kubelet-csr-approver