Packer: Set label custom_image=archlinnux

packer/archlinux.json

@@ -6,6 +6,9 @@
     "builders": [{
         "type": "hcloud",
         "snapshot_name": "archlinux-{{ isotime \"2006-01-02T15:04\" }}",
+        "snapshot_labels": {
+            "custom_image": "archlinux"
+        },
         "token": "{{ user `hetzner_cloud_api_key` }}",
         "image": "ubuntu-18.04",
         "server_type": "cx11",