Update to slf4j 2.x

[hvesalai]

SLF4J has advanced to version 2.x (latest is https://github.com/qos-ch/slf4j/releases/tag/v_2.0.9). Is there a reason to keep Log4s depending on 1.7.x?

[rossabaker]

I've generally kept libraries pinned to 1.x and let applications pull in 2.x. This maintains maximal compatibility with no compromise in functionality that I've seen.

Related discussion on log4cats from 2022. I haven't revisited since, and maybe there are new compelling reasons: typelevel/log4cats#686