Set apiVersion and languageVersion to 2.0 to ensure backwards compatibility

[hugoncosta]

Address #9032 by setting apiVersion and languageVersion to 2.0. This ensures that the code can be compiled with Kotlin 2.2.0+ but users as low as 1.9.0 are able to run this without being forced to update. For reference, 2.2.0 supports compilation as low as 1.6.0.

Compiled locally, seems to work fine, but my laptop is not setup to compile the Android modules btw

[hugoncosta]

Sorry about that - not really used to these workflows + I don't have an Android SDK on my machine. I think this should be it 🤞

[hugoncosta]

I think I have found an easier path, and especially one that doesn't require us to change much - the source code is already 2.0 compatible, only the tests aren't, and they don't need to be, so why bother? The change is now focusing only on "main" source sets, leaving the tests to use any 2.0+ feature.

[yschimke]

I'll wait for https://github.com/square/okio/pull/1690 to land before this

[yschimke]

The Okio PR sounds promising, so I'll land this assuming it will also. Thanks for the PR.

Are you ok with the suggested changes for matching tasks I accepted? They are also on the Okio PR.

[yschimke]

Shit, I think that suggestion broke it.

Not sure if we need to follow this https://kotlinlang.org/docs/whatsnew21.html#new-api-for-kotlin-gradle-plugin-extensions

[Goooler]

Yeah, we can try out something like

extensions.configure<KotlinBaseExtension> {
  (this as HasConfigurableKotlinCompilerOptions<*>?)?.let {
    compilerOptions {
      apiVersion = KotlinVersion.KOTLIN_2_0
      languageVersion = KotlinVersion.KOTLIN_2_0
    }
  }
}