Update okhttp to 3.12.3

    // We'll use 3.12 for now, but this branch won't receive feature updates anymore. Security

    // updates are limited to Dec 2020, so we'll have to update to 3.13 until then. On Android,

    // using 3.13 will raise the required SDK level to Android 5.

    const val okhttpVersion = "3.12.2"

    const val okhttpVersion = "3.12.3"

    // XmlPullParser library

    const val xpp3Version = "1.1.6"