Giving an integer value as default for a double, causes the validation to fail

Reproduce the failure with the provided openapi.yaml using openapi_spec_validator.readers.read_from_filename and validate_spec. Compare validation of integer and floating-point defaults for a number with format double; done means the intended behavior is established and covered by a regression test, while preserving the valid 15.0 case.

Hi,
I noticed that there is a breaking change from 0.2.9 to 0.3.0, but I am not sure if it is intentional or not.

tl;dr: an integer is no longer considered a valid (default) value for a double. In the example below, 15 fails the validation, but 15.0 is fine.

PS: I am using openapi-spec-validator through the connexion library.

Steps to reproduce

python -m venv .venv
source .venv/bin/activate
pip install "openapi-spec-validator@0.3.0"

>>> from openapi_spec_validator import validate_spec
>>> from openapi_spec_validator.readers import read_from_filename
>>>
>>> spec_dict, spec_url = read_from_filename('./openapi.yaml')
>>> validate_spec(spec_dict)

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<current working directory>/.venv/lib/python3.9/site-packages/openapi_spec_validator/shortcuts.py", line 7, in validate
    return validator_callable(spec, spec_url=spec_url)
  File "<current working directory>/__app__/.venv/lib/python3.9/site-packages/openapi_spec_validator/validators.py", line 48, in validate
    raise err
openapi_spec_validator.exceptions.OpenAPIValidationError: 15 is not a 'double'

Failed validating 'format' in schema:
    {'default': 15,
     'format': 'double',
     'maximum': 60,
     'minimum': 15,
     'nullable': False,
     'type': 'number'}

On instance:
    15

where openapi.yaml is defined as

openapi: "3.0.3"
info:
  title: API
  version: "1.0.0"

servers:
  - url: http://localhost/api
    description: Used for local development.
paths:
  /foo:
    get:
      parameters:
        - in: query
          name: duration
          required: false
          schema:
            type: number
            format: double
            default: 15
            maximum: 60
            minimum: 15
          example: 53

      responses:
        200:
          description: ""
          content:
            text/plain: {}

Changing default: 15 to default: 15.0 works as expected.

In version 0.2.9, the OpenAPI specification above was considered valid.