prepared to build a TLS API for Kotlin/Native.

    We'd prefer a multiplatform HTTP client API that's backed by OkHttp on Android and JVM, and
    other engines on other platforms. [Ktor] does this pretty well today!

 *  Breaking: Use `kotlin.time.Duration` in APIs like `OkHttpClient.Builder.callTimeout()`. This
    update also drops support for the `DurationUnit` functions introduced in earlier alpha releases
    of OkHttp 5.