Apple has recently seeded the first beta of watchOS 3.1.3 to developers. This comes a little over a week after the release of 3.1.1. While watchOS 3.1.3 is the version that is seeded, we haven’t seen 3.1.2 yet. That means that Apple is still working on that version and is not planning on seeded it to developers.
To get this version, developers can go to the Watch app and find it under software updates. If you do not have the beta testing profile installed yet, you can go to the Apple Developer Center and get it from there.