Bump to 2.0.0-SNAPSHOT.

[sjrd]

So that we can release v2.0.0 with the Scala 3 artifact.

Fixes #451.

[gzm0]

I have commented on #451 regarding this.

[gzm0]

So, I'm still unsure about what the community consensus is regarding that. But the major bump in itself is correct. So I'm going to approve this.

@sjrd if you want my opinion on what to do with regards to this, I'll need significantly more time, because I need to learn how the entire dotty compat thing is supposed to work and how it works in practice. I'm not able to follow the conversation in #451.

[sjrd]

Given the reactions at #451 (comment), I'm going to merge this, and proceed with a bunch of cleanups.

[armanbilge]

@sjrd Thanks for going forward with this! :) Can I help with any/all of the cleanup tasks? I ask, just to make sure that there aren't any duplicate efforts.

[sjrd]

I have started doing the cleanups today. If I have to move to other things, I'll let you know.