[BUG] Python pattern re.search('r incorrect in generated server model

Created by: nathan5280

Generators aren't consistently escaping the regex patterns for python and python-flask.

Description

openapi-codegen python and python-flask generate different regex escapes.

Generated Client

        if business_addr_zip is not None and not re.search(r'^\d{5}(?:[-\s]\d{4})?$', business_addr_zip):  # noqa: E501

Generated Server

        if business_addr_zip is not None and not re.search(r'^\\d{5}(?:[-\\s]\\d{4})?$', business_addr_zip):  # noqa: E501

The client seems fine, but the server is double escaped.

openapi-generator version

docker image https://hub.docker.com/r/openapitools/openapi-generator-cli/

OpenAPI declaration file content or url

Specification:

    PlaceQuery:
      properties:
        data:
          properties:
            entity_name:
              type: string
            physical_address:
              properties:
                business_addr_zip:
                  pattern: ^\d{5}(?:[-\s]\d{4})?$
                  type: string
              required:
                - business_addr_zip
              type: object
          required:
            - entity_name
            - physical_address
          type: object
      required:
        - data
      type: object

Command line used for generation

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