Fix mail server VM backups

nodes/mail.kosmos.org.json

@@ -10,7 +10,7 @@
     "fqdn": "mail.kosmos.org",
     "os": "linux",
     "os_version": "5.15.0-1048-kvm",
-    "hostname": "mail",
+    "hostname": "mail.kosmos.org",
     "ipaddress": "192.168.122.131",
     "roles": [
       "base",