[BUG][PYTHON] Decoding accents problem using json.dumps() when using ascii characters

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 problem occurs when using french accents where it would convert the accents into unicode code points instead of keeping the utf8 encoding. The problem occurs in the rest.mustache template where the generated code doesn't allow ensure_ascii to be set as false.

openapi-generator version

Tested on 7.6.0

OpenAPI declaration file content or url

request_body = None
                    if body is not None:
                        request_body = json.dumps(body)
                    r = self.pool_manager.request(
                        method,
                        url,
                        body=request_body,
                        timeout=timeout,
                        headers=headers,
                        preload_content=False
                    )

Generation Details

Basic generation of the rest.mustache template

Steps to reproduce

When sending a request with rest.mustache template using french accents. Ex: é ---> \u00c3\u00a9

Suggest a fix

request_body = None
                    if body is not None:
                        request_body = json.dumps(body, ensure_ascii={{ensureAscii}})
                    r = self.pool_manager.request(
                        method,
                        url,
                        body=request_body,
                        timeout=timeout,
                        headers=headers,
                        preload_content=False
                    )

Start with the generated Python request-body code in the rest.mustache template and reproduce the issue with a French accented character such as é. Check how json.dumps handles ensure_ascii there; done means the generated client preserves the intended UTF-8 encoding while retaining the suggested ensureAscii configuration.