Zio-http does not send the correct Content-Type response header.

[ffprivacy]

Describe the bug
Zio-http does not send the correct Content-Type response header. When client send the Accept header to plain/text.

To Reproduce
Steps to reproduce the behaviour:

val mediaTypeJsonOrTextEndpoint = Endpoint(RoutePattern.POST / "api" / "mediaTypeJsonOrText")
        .outCodec(HttpCodec.content[Greeting](MediaType.text.plain))
        .outCodec(HttpCodec.content[Greeting](MediaType.application.json))
routes = routes :+ mediaTypeJsonOrTextEndpoint.implement {
    case (name) => {
        ZIO.succeed(new Greeting(name="greeting"))
    }
}
endpoints = endpoints :+ mediaTypeJsonOrTextEndpoint
var openAPI       = OpenAPIGen.fromEndpoints(title = "Server OpenAPI", version = "1.0", bookEndpoint, endpoints: _*)
val swaggerRoutes = SwaggerUI.routes("openapi", openAPI)
for(server <- openAPI.servers) {
    println(f"server=${server}")
}

routes = routes ++ swaggerRoutes.sandbox

val app = routes.sandbox

val run = Server.serve(app).provide(Server.default, Client.default).exitCode

1. Select response type text/plain (set the Accept header) in the swagger ui in the mediaTypeJsonOrText path
2. Click execute
3. Response is still json, zio-http has not choosed the right codec

Expected behaviour
Changing the Accept header must cause the client to send Content-Type: plain/text as response and the body as this type

Screenshots

Desktop (please complete the following information):

• OS: ubuntu
• Browser: brave
• Version: Version 1.74.48 Chromium: 132.0.6834.83 (Build officiel) (64 bits)](https://brave.com/latest/)