[BUG][Python] python-fastapi 7.9.0 generates wrong imports

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

An import is generated that does not exist.

openapi-generator version

7.9.0

OpenAPI declaration file content or url

The code for the yaml spec can be found here: https://github.com/bbc/tams/tree/main/api

Generation Details

This is a snippet of the file it generates with the relevant to the issue imports:

from pydantic import ConfigDict, Field
from openapi_server.models.object import object
try:
    from typing import Self
except ImportError:
    from typing_extensions import Self

class MediaBucketObjectStore(object):
    ...

The issue is the imported object, which doesn't exist.

I believe the generated file should be this:

from pydantic import ConfigDict, Field, BaseModel
try:
    from typing import Self
except ImportError:
    from typing_extensions import Self

class MediaBucketObjectStore(BaseModel):
    ...

Steps to reproduce

build-server-local-fastapi:
	docker run --user ${USER}:${GROUP} --rm \
                   -v ${PWD}:/local openapitools/openapi-generator-cli:v${GEN_VER} generate \
				   --additional-properties=apiNameSuffix=controller_impl \
                   -t /local/.templates/7.9.0/python_fastapi/.openapi-generator-server/ \
                   -i /local/openapi.yaml \
                   -g python-fastapi \
                   -o /local/python_fastapi/

Start with the linked OpenAPI specification and reproduce the issue using the Docker command in the report, including the custom .templates/7.9.0/python_fastapi template path. Inspect the generated model imports and compare them with the expected BaseModel output; done means the generated FastAPI model no longer imports the nonexistent object and uses the expected base model.