Migrating from Swagger 2.0 to OpenAPI 3.0

[Paul-vrn]

I wanted to migrate the Swagger 2.0 specification of the project to OpenAPI 3.0 to achieve better compatibility with OpenAPI code generators and to keep the project up-to-date with the latest standards.
Additionally, for personal needs, I have already recreated and corrected the specification in OpenAPI 3.0 to accurately reflect the response payloads and match the actual behavior of the API requests.

So if it's ok, I can open a pull request 🙂

[n1ngu]

Hey @Paul-vrn . Thanks for the initiative and the collaborative spirit.

I am sorry to redirect you to #442

There is little use for yet another abandoned pull-request unless the project is rebooted, and that seems unfeasible. For all it's worth, just keep those improvements in your fork and announce that in #375 / #399

[Newmmen]

@Paul-vrn Hi, could you please share Open Api 3.0 specification?