Upgrade to Scala 3.1.3?

[armanbilge]

Notably, it includes lampepfl/dotty#14318. The bug it fixes seems to cause all sorts of problems when trying to do things with sourcemaps.

I realize this lib is mostly facade where line numbers may not matter, but there are a few places where it could.

Edit: note that this would force an update to Scala.js 1.7 as well.

[armanbilge]

I will move ahead with this.

1. The official advice for Scala 3 is to upgrade.
   https://www.scala-lang.org/blog/2022/08/17/long-term-compatibility-plans.html
2. Scala.js 1.7.0 was released over a year ago.
   https://www.scala-js.org/news/2021/08/04/announcing-scalajs-1.7.0/