Doesn't support remote schema in $ref

[francbartoli]

def resolve_schema(self, schema_ref):
        schema_name = schema_ref.split('/')[-1]
        schema = self.spec['components']['schemas'][schema_name]
        ...

If schema_ref is a remote URI the following error is returned:

Traceback (most recent call last):
  ...
  File "/Users/francbartoli/code/fastgeoapi/.venv/lib/python3.11/site-packages/fencer/cli.py", line 34, in run
    api_spec.load_endpoints()
  File "/Users/francbartoli/code/fastgeoapi/.venv/lib/python3.11/site-packages/fencer/api_spec.py", line 255, in load_endpoints
    body=self.resolve_body(self.paths[path][method].get('requestBody')),
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/francbartoli/code/fastgeoapi/.venv/lib/python3.11/site-packages/fencer/api_spec.py", line 273, in resolve_body
    schema = self.resolve_schema(body['content']['application/json']['schema']['$ref'])
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/francbartoli/code/fastgeoapi/.venv/lib/python3.11/site-packages/fencer/api_spec.py", line 293, in resolve_schema
    schema = self.spec['components']['schemas'][schema_name]
             ^^^^
KeyError: 'execute.yaml'