Update scala to 2.13.12

[valencik]

This PR bumps the version of Scala to 2.13.12.

Without this, I was running into an error on sbt run:

error: scala.reflect.internal.FatalError:                                                                                                                                  
  bad constant pool index: 0 at pos: 48445
...
Error compiling the sbt component 'compiler-bridge_2.13'

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[daddykotex]

Thanks Andrew!

Without this, I was running into an error on sbt run:

Do you mean that you can't compile on older version, like the one that was set before?

[daddykotex]

I'll merge even w/o the CLA, as there is no IP involved in such a version bump

[valencik]

Thanks Andrew!

Without this, I was running into an error on sbt run:

Do you mean that you can't compile on older version, like the one that was set before?

As in a brand new sbt new disneystreaming/smithy4s.g8 was failing on sbt run until I bumped the scala version manually.
But yes, compile also fails.