Upgrade kotlin and log4j versions

[u-ways]

Hello,

It seems that the Log4j version of the Kotlin API is out of date. On top of that, the Kotlin version hasn't been updated for the past 2 years.

I have did a code analysis scan and found no incompatibles, tests are passing, and everything seems to be working as excepted.

Reasons to upgrade to 1.8.0 that are relevant:

• 1.8.0 - Improved kotlin-reflect performance
• 1.6.0 - Further Improvements to type inference for recursive generic types
• 1.5.30 - Improvements to type inference for recursive generic types
• 1.5.0 - Inline classes are released as Stable

And lots of other performance improvements overall...

Changes

• Upgrade log4j to 2.19.0
• Upgrade Kotlin to 1.8.0
• kotlinx.coroutines to 1.6.4

Trivial changes - Feel free to amend as needed. :)

[u-ways]

@jvz Can you have a look please?

[jvz]

The Kotlin API is a minimum version requirement. I've been using this library with Kotlin 1.4.x, 1.7.x, and 1.8.x. The Log4j version update is good, though!

[u-ways]

I see, that makes sense, thanks for letting me know, I am closing this one and opening a more appropriate PR for Log4j upgrade only.