attempt to fix updating a NIC with a missing MAC

[lmacken]

This patch is an attempt to fix an error with doing --update-all on machines that have an existing NIC in netbox with missing MAC addresses. This state triggered this exception:

DEBUG:urllib3.connectionpool:[https://netbox.farmgpu.net:443](https://netbox.farmgpu.net/) "GET /api/dcim/interfaces/?mac_address=90%3A5a%3A08%3A0e%3A30%3A1c&name=ens4059f0np0&device_id=119&limit=0 HTTP/1.1" 200 None
INFO:root:Interface 90:5a:08:0e:30:1c not found, creating..
INFO:root:Creating NIC ens4059f0np0 (90:5a:08:0e:30:1c) on intel-minio-1
DEBUG:urllib3.connectionpool:[https://netbox.farmgpu.net:443](https://netbox.farmgpu.net/) "POST /api/dcim/interfaces/ HTTP/1.1" 400 67
Traceback (most recent call last):
  File "/home/fgpu/myenv/bin/netbox_agent", line 8, in <module>
    sys.exit(main())
             ^^^^^^
  File "/home/fgpu/myenv/lib/python3.12/site-packages/netbox_agent/cli.py", line 63, in main
    return run(config)
           ^^^^^^^^^^^
  File "/home/fgpu/myenv/lib/python3.12/site-packages/netbox_agent/cli.py", line 56, in run
    server.netbox_create_or_update(config)
  File "/home/fgpu/myenv/lib/python3.12/site-packages/netbox_agent/server.py", line 425, in netbox_create_or_update
    self.network.create_or_update_netbox_network_cards()
  File "/home/fgpu/myenv/lib/python3.12/site-packages/netbox_agent/network.py", line 463, in create_or_update_netbox_network_cards
    interface = self.create_netbox_nic(nic)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/fgpu/myenv/lib/python3.12/site-packages/netbox_agent/network.py", line 297, in create_netbox_nic
    interface = self.nb_net.interfaces.create(**params)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/fgpu/myenv/lib/python3.12/site-packages/pynetbox/core/endpoint.py", line 417, in create
    ).post(args[0] if args else kwargs)
      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/fgpu/myenv/lib/python3.12/site-packages/pynetbox/core/query.py", line 370, in post
    return self._make_call(verb="post", data=data)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/fgpu/myenv/lib/python3.12/site-packages/pynetbox/core/query.py", line 260, in _make_call
    raise RequestError(req)
pynetbox.core.query.RequestError: The request failed with code 400 Bad Request: {'__all__': ['Interface with this Device and Name already exists.']}

This patch seems to update the existing device with the new MAC address properly.