[nancy][grouille-1] change mac address of BMC

data/grid5000/sites/nancy/clusters/grouille/nodes/grouille-1.json

@@ -272,7 +272,7 @@
       "interface": "Ethernet",
       "ip": "172.17.79.1",
       "kavlan": false,
-      "mac": "70:b5:e8:e7:3c:74",
+      "mac": "70:b5:e8:cf:5c:b6",
       "management": true,
       "mountable": false,
       "mounted": false,