Drop Scala 2.12

[armanbilge]

Scala Toolkit supports 2.12. All of our libraries do so far, so it's not any extra effort to do it here.

But, why. Here you go @SethTisue 😜

[TonioGela]

Since we're at 0.0.2 we can declare that _2.12::0.0.1 and _2.12::0.0.2 were build misconfigurations ¯\_(ツ)_/¯ 😇

[SethTisue]

I suggested the same for the Scala Toolkit over at scala/toolkit#3 . not sure how to interpret the silence, maybe they're discussing it internally?

anyway, the arguments I made there apply here as well, I think:

I can see the temptation to let the answer be "yes", since the libraries that have been selected all work on 2.12.
Scala 2.12 isn't EOL, but it's in a semi-EOL state where anything more than the lightest, most minimal maintenance is only happening because of a single commercial sponsor.
I think we could reasonably say, if you want to use the toolkit you should be on 2.13 or 3, we aren't interested in offering this brand-new thing on a half-dead Scala version series.
Even if supporting 2.12 wouldn't cause us any special difficulty at the moment, it might cause us trouble and slow us down down the road, and since the toolkit is new, now's our chance to just not support 2.12 right from the very start.

[TonioGela]

Okay, we can delegate the decision to them and decide after receiving an answer. If the toolkit won't support Scala 2.12 anymore, then there's no reason for us to do the same (even taking in consideration the fact that the toolkit can be used as a vanilla dependency in sbt/mill)

[armanbilge]

Scala Toolkit is dropping 2.12, so we can too.

scala/toolkit#3 (comment)