Describe the bug
During OpenAPI metadata-ingestion there is a get_endpoints method that wrongly assumes that a Path Item Object is a dictionary with only string keys (methods) and Operation Object values. This is not the case for the keys parameters and servers which map to array values

This code fails: https://github.com/datahub-project/datahub/blob/v0.13.1/metadata-ingestion/src/datahub/ingestion/source/openapi_parser.py#L123C9-L123C30 with TypeError: list indices must be integers or slices, not str when the first item in the Path Item Object is a servers or parameters since their values are Arrays and not Operation Objects

It is valid to have a parameters key or a servers key that contain arrays: https://spec.openapis.org/oas/v3.0.1#path-item-object

To Reproduce
Steps to reproduce the behavior:

1. Example Swagger snippet:

paths:
    parameters:
      - name: parameter
         in: query
    get:
       responses:
           ...

Expected behavior
method = list(p_o)[0] should not assume that a method is the first item. It could be servers or parameters

This could fix it:

method = next(key for key in list(p_o) if key not in {'servers', 'parameters'})

Desktop (please complete the following information):

• OS: Linux
• Browser: N/A
• Version: v0.13.1

Additional context
Problematic code: https://github.com/datahub-project/datahub/blob/v0.13.1/metadata-ingestion/src/datahub/ingestion/source/openapi_parser.py#L123C9-L123C30

Path item object spec: https://spec.openapis.org/oas/v3.0.1#path-item-object