Use correct response code in push mirror creation response in v1_json.tmpl (#25476)

Use correct response code in push mirror creation response in v1_json.tmpl (#25476)

In the process of doing a bit of automation via the API, we've
discovered a _small_ issue in the Swagger definition. We tried to create
a push mirror for a repository, but our generated client raised an
exception due to an unexpected status code.

When looking at this function:

https://github.com/go-gitea/gitea/blob/3c7f5ed7b5bff347198cbb26492e6354ea42733b/routers/api/v1/repo/mirror.go#L236-L240

We see it defines `201 - Created` as response:

https://github.com/go-gitea/gitea/blob/3c7f5ed7b5bff347198cbb26492e6354ea42733b/routers/api/v1/repo/mirror.go#L260-L262

But it actually returns `200 - OK`:

https://github.com/go-gitea/gitea/blob/3c7f5ed7b5bff347198cbb26492e6354ea42733b/routers/api/v1/repo/mirror.go#L373

So I've just updated the Swagger definitions to match the code😀

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Co-authored-by: Giteabot <teabot@gitea.io>