This change fixes a [CSRF](https://en.wikipedia.org/wiki/Cross-site_request_forgery) security vulnerability when using cookies for authentication in path operations with JSON payloads sent by browsers.

In versions lower than `0.65.2`, FastAPI would try to read the request payload as JSON even if the `content-type` header sent was not set to `application/json` or a compatible JSON media type (e.g. `application/geo+json`).