[BUG] [Python-fastapi] Missing await in generated asynchronous endpoints

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

The asynchrony of the endpoints is not propagated to their corresponding base api methods.

openapi-generator version

v7.0.1 and snapshot version.

OpenAPI declaration file content or url

Here is an example of the OpenAPI declaration file content:

https://gist.github.com/reyescabello/6cd965708fd0b03e8eadb9f3c0c0a899

Generation Details

Generated with jar:

java -jar openapi-generator-cli.jar generate -i openapi.yml -g python-fastapi -o openapi_server

Suggest a fix

The generated endpoints have the following format:

product_api.py

async def find_all_products(
) -> List[Product]:
    """The user must have any permission in the application."""
    return BaseProductApi.subclasses[0]().find_all_products()

product_api_base.py

def find_all_products(
    self,
) -> List[Product]:
    """The user must have any permission in the application."""
    ...

when they should be:

product_api.py

async def find_all_products(
) -> List[Product]:
    """The user must have any permission in the application."""
    return await BaseProductApi.subclasses[0]().find_all_products()

product_api_base.py

async def find_all_products(
    self,
) -> List[Product]:
    """The user must have any permission in the application."""
    ...

Start by tracing the python-fastapi generation invoked by the documented java -jar command, then compare the generated product_api.py and product_api_base.py examples with the linked OpenAPI declaration. Regenerate the sample and verify that asynchronous endpoints and their base methods both use await consistently.