Upgrade to gradle 8.x

[juherr]

The automatic upgrade bot is failing:

FAILURE: Build failed with an exception.
  
  * Where:
  Settings file '/home/runner/work/testng/testng/settings.gradle.kts' line: 33
  
  * What went wrong:
  There is no feature named VERSION_CATALOGS

See instructions for manual upgrade: https://docs.gradle.org/current/userguide/upgrading_version_7.html#changes_7.5

[juherr]

@vlsi some help will be welcome.

Current status is:

> Task :build-logic:code-quality:compileKotlin FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':build-logic:code-quality:compileKotlin'.
> Inconsistent JVM-target compatibility detected for tasks 'compileJava' (21) and 'compileKotlin' (11).
  
  Consider using JVM Toolchain: https://kotl.in/gradle/jvm/toolchain
  Learn more about JVM-target validation: https://kotl.in/gradle/jvm/target-validation 

[vlsi]

We need something like apache/jmeter#5989

[juherr]

@vlsi Thanks!

It's better now but something is not going well with the kotlin block:
ac70c8e#diff-c6bae4a70e57445a9f1b127f5ab3dbef8c30ccd7d5f4d98f9a9cf85787babb91R13-R17

> Task :build-logic:jvm:compileKotlin FAILED
e: file:///Users/juherr/Projects/Perso/testng/build-logic/jvm/src/main/kotlin/testng.kotlin-library.gradle.kts:15:9 Unresolved reference: languageVersion

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':build-logic:jvm:compileKotlin'.
> A failure occurred while executing org.jetbrains.kotlin.compilerRunner.GradleCompilerRunnerWithWorkers$GradleKotlinCompilerWorkAction
   > Compilation error. See log for more details

Do you have another good link to share?

[juherr]

Forget it. It looks working as expected when I remove the block.

Gradle is definitely too complicated for me 🤣

[vlsi]

Fixed in #3067