[BUG] Unnecessary Parenthesis on Python Client Code

Created by: wy193777

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• What's the version of OpenAPI Generator used?
• Have you search for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Bounty to sponsor the fix (example)

Description

The parenthesis around data is unnecessary. Can causing mypy linter give `undefined variable https://github.com/OpenAPITools/openapi-generator/blob/0eb385c0d6497c38c09b42158b2d66109b78b15b/modules/openapi-generator/src/main/resources/python/api.mustache#L57

openapi-generator version

Current code on master.

Suggest a fix

Delete the unnecessary parenthesis.