Bump the Scala Version to 2.13.2

[iamrecursion]

Summary

We're currently on scala 2.13.1, but 2.13.2 has come out recently. However, many of our dependencies haven't been updated yet. This task is to revisit checking our dependencies' compatibility, and updating our scala version when they become compatible.

Value

We'll be up to date with scala, and obtain better compatibility with later JDK releases (so that we may be able to revisit building on top of GraalVM Java 11 instead of Java 8. Additionally we get configurable warnings and local warning suppression via @nowarn.

Specification

• Check the compatibility of all of our dependencies.
• Once they are all compatible, bump the build version of scala to 2.13.2.
• Enable -Xfatal-warnings, and fix the warnings that can be fixed. If the warnings are spurious, please use the new @nowarn mechanism to suppress them locally.

Acceptance Criteria & Test Cases

• We're on scala 2.13.2.