Fix inventory.py to work with nautobot 1.3.1

[gneville-ot]

Since upgrading to nautobot 1.3.1 the inventory plugin errors with:

  File "/home/appuser/.ansible/collections/ansible_collections/networktocode/nautobot/plugins/inventory/inventory.py", line 1349, in main
    self.fetch_api_docs()
  File "/home/appuser/.ansible/collections/ansible_collections/networktocode/nautobot/plugins/inventory/inventory.py", line 1074, in fetch_api_docs
    self.allowed_device_query_parameters = [p["name"] for p in openapi["paths"]["/dcim/devices/"]["get"]["parameters"]]

It seems /api was missing from the paths when getting device and vm query parameters, adding it resolves the issue.

[glennmatthews]

Interesting, we didn't intentionally change the paths in the OpenAPI schema in Nautobot 1.3, this may have been an unintended consequence of the move to OpenAPI 3.0 in nautobot/nautobot#1544. This change looks safe enough as a workaround but this may be worth considering to be a bug in Nautobot as well.

[FragmentedPacket]

@gneville-ot mind fixing the linting? Once tests pass we can get this merged in.