Support Scala 2.13 #147
Description
There are two reasons I'm reluctant to do this at the moment.
The first is that Cats doesn't yet have non-milestone, non-RC releases for 2.13. For a number of my other projects I've been tracking the pre-final Cats 2.0.0 releases, but this is a library that I'm not personally using at the moment, and that I don't think carries all that much value as an example for testing things out, so I didn't really want to start publishing a bunch of milestones and RCs. Now Cats 2.0.0 is likely only a week or so away, so I think it definitely makes sense to wait.
The second reason is that while the latest release of Twitter Util (19.8.1) introduced support for Scala 2.13 a couple of weeks ago, Finagle doesn't support 2.13 yet. I hate maintaining builds where submodules have different cross-versions, so my plan was to wait for Finagle.
That said, if someone wants to open a PR updating to Cats 2.0.0-RC2 and setting up the build so that cross-building and publishing works cleanly, I'd be happy to review it and run the release. Otherwise this will wait for Cats 2.0.0 and Finagle.