Remove itype from vm_interface

[gstorme]

Upon running a vcenter sync, the interfaces of virtual machine objects would always be updated with a PATCH, but without making any real changes.
The change would be visible in the GUI but without any difference.

Also, the interface type on a vm_interface is removed in Netbox 2.9, since this is always virtual.

GET /api/virtualization/interfaces/1924/

{
  "id": 1924,
  "virtual_machine": {
    "id": 836,
    "url": "https://netbox.masked-ops.net/api/virtualization/virtual-machines/836/",
    "name": "masked-virtual_machine"
  },
  "name": "vNIC0",
  "type": {
    "value": "virtual",
    "label": "Virtual"
  },
  "enabled": true,
  "mtu": null,
  "mac_address": "00:50:56:98:00:BF",
  "description": "",
  "mode": null,
  "untagged_vlan": null,
  "tagged_vlans": [],
  "tags": [
    "vCenter",
    "Synced",
    "masked-vcenter006"
  ]
}

Debug log upon sync doing a unnecessary PATCH, changing nothing, but reporting a change:

[DEBUG] Sending GET to 'https://netbox.masked-ops.net/api/virtualization/interfaces/?virtual_machine=masked-virtual_machine&name=vNIC0&?tag=masked-vcenter006' with data 'None'.
[DEBUG] Received HTTP Status 200.
[DEBUG] NetBox GET request OK; returned 200 status.
[DEBUG] NetBox virtual_interfaces object 'vNIC0' already exists. Comparing values.
[DEBUG] vc_data[virtual_machine] and nb_data[virtual_machine] contain dictionary. Evaluating.
[DEBUG] vc_data[virtual_machine][name] and nb_data[virtual_machine][name] values match.
[DEBUG] Final dictionary compare result: True
[DEBUG] vc_data[virtual_machine] and nb_data[virtual_machine] values match.
[DEBUG] vc_data[name] and nb_data[name] values match.
[DEBUG] vc_data[itype] not a valid key in nb_data[itype].
[DEBUG] vc_data[itype] and nb_data[itype] values do not match.
[INFO] NetBox virtual_interfaces object 'vNIC0' do not match current values.
[DEBUG] Merging tags between vCenter and NetBox object.
[DEBUG] Sending PATCH to 'https://netbox.masked-ops.net/api/virtualization/interfaces/1924/' with data '{'virtual_machine': {'name': 'masked-virtual_machine'}, 'name': 'vNIC0', 'itype': 'virtual', 'enabled': True, 'mac_address': '00:50:56:98:00:BF', 'tags': ['masked-vcenter006', 'vCenter', 'Synced']}'.
[DEBUG] Received HTTP Status 200.
[DEBUG] NetBox PATCH request OK; returned 200 status.