Is your feature request related to a problem? Please describe.
When I have a type discriminator with a mapping where the field for the mapping is an enum, I'd like for the generated code to use the enum values for the literals on the discriminator field. Arguably, this should be a feature request for OpenAPI itself, but maybe it's something this library could help with. I'll show an example below (the example is taken from #1760)
Example input

Example schema:

---
components:
  schemas:
    Request:
      oneOf:
        - $ref: '#/components/schemas/RequestV1'
        - $ref: '#/components/schemas/RequestV2'
      discriminator:
        propertyName: version
        mapping:
          v1: '#/components/schemas/RequestV1'
          v2: '#/components/schemas/RequestV2'

    RequestVersionEnum:
      type: string
      description: this is not included!
      title: no title!
      enum:
        - v1
        - v2

    RequestBase:
      properties:
        version:
          $ref: '#/components/schemas/RequestVersionEnum'
      required:
        - version

    RequestV1:
      allOf:
        - $ref: '#/components/schemas/RequestBase'
      properties:
        request_id:
          type: string
      required:
        - request_id
    RequestV2:
      allOf:
        - $ref: '#/components/schemas/RequestBase'

Desired output

class RequestVersionEnum(str, Enum):
    v1 = 'v1'
    v2 = 'v2'

class RequestBase(BaseModel):
    version: RequestVersionEnum

class RequestV1(RequestBase):
    request_id: str = Field(..., description='there is description', title='test title')
    version: Literal[RequestVersionEnum.v1]


class RequestV2(RequestBase):
    version: Literal[RequestVersionEnum.v2]

class Request(RootModel[Union[RequestV1, RequestV2]]):
    root: Union[RequestV1, RequestV2] = Field(..., discriminator='version')

Describe the solution you'd like
Likely would require a new argument to consider the type discriminator fields as enum values, not just strings

Additional context
Without this mypy complains, basically of the following:

Incompatible types in assignment (expression has type "Literal['v1']", base class "RequestBase" defined the type as "RequestVersionEnum")