Support for scientific notation

Start with the supplied OpenAPI 3.0.3 schema and its maximum: 1e2 value, comparing it with the equivalent maximum: 100 case. Trace how the validator handles the scientific-notation value, then verify that the reported schema validates without weakening the numeric constraint checks.

This schema with scientific notation maximum: 1e2

openapi: 3.0.3
info:
  title: scientific notation
  description: ...
  version: 1.0.0
paths:
  /pet:
    put:
      tags:
        - pet
      summary: ...
      description: ...
      operationId: updatePet
      requestBody:
        description: ...
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/Pet'
      responses:
        '200':
          description: Successful operation
components:
  schemas:
    Pet:
      type: object
      properties:
        id:
          type: integer
          format: int64
          maximum: 1e2
          example: 10

results in this unexpected failure

# Validation Error

{'description': '...', 'content': {'application/json': {'schema': {'type': 'object', 'properties': {'id': {'type': 'integer', 'format': 'int64', 'maximum': '1e2', 'example': 10}}}}}} is not valid under any of the given schemas

Failed validating 'oneOf' in schema['properties']['paths']['patternProperties']['^\\/']['patternProperties']['^(get|put|post|delete|options|head|patch|trace)$']['properties']['requestBody']:
    {'oneOf': [{'$ref': '#/definitions/RequestBody'},
               {'$ref': '#/definitions/Reference'}]}

On instance['paths']['/pet']['put']['requestBody']:
    {'content': {'application/json': {'schema': {'properties': {'id': {'example': 10,
                                                                       'format': 'int64',
                                                                       'maximum': '1e2',
                                                                       'type': 'integer'}},
                                                 'type': 'object'}}},
     'description': '...'}


# Due to one of those errors

## {'type': 'object', 'properties': {'id': {'type': 'integer', 'format': 'int64', 'maximum': '1e2', 'example': 10}}} is not valid under any of the given schemas

Failed validating 'oneOf' in schema[0]['properties']['content']['additionalProperties']['properties']['schema']:
    {'oneOf': [{'$ref': '#/definitions/Schema'},
               {'$ref': '#/definitions/Reference'}]}

On instance['content']['application/json']['schema']:
    {'properties': {'id': {'example': 10,
                           'format': 'int64',
                           'maximum': '1e2',
                           'type': 'integer'}},
     'type': 'object'}


## '$ref' is a required property

Failed validating 'required' in schema[1]:
    {'patternProperties': {'^\\$ref$': {'format': 'uri-reference',
                                        'type': 'string'}},
     'required': ['$ref'],
     'type': 'object'}

On instance:
    {'content': {'application/json': {'schema': {'properties': {'id': {'example': 10,
                                                                       'format': 'int64',
                                                                       'maximum': '1e2',
                                                                       'type': 'integer'}},
                                                 'type': 'object'}}},
     'description': '...'}
...

If I change maximum: 1e2 to maximum: 100, it validates without error.