title: Kotlinx.Serialization deserializing dates
body: <p>I'm having a hard time finding documentation on how to deserialize date fields.
  How do i achieve this? Most solutions i found on SO don't work or they use classes that are no longer available</p>
  <pre><code>@Serializable
  data class Dashboard(
      val someNumber: Int,
      val someDate: Date? // Custom Deserialization from unix timestamp
  )
  </code></pre>
  <p><strong>EDIT:</strong> Most solution i found use <code>PrimitiveSerialDescriptor</code> which seems to be not available</p>