Update the Gradle snippet for Kotlin DSL

[LouisCAD]

Gradle now recommends to use Kotlin DSL over Groovy DSL. This updates the dependency snippet for Gradle to be compatible with both.

[saudet]

Thanks! Could you do the same for javacpp and javacpp-presets?

[LouisCAD]

I can, but those are not in this repo

[LouisCAD]

Done in:

• Update the Gradle snippet for Kotlin DSL javacpp#749
• Update the Gradle snippet for Kotlin DSL javacpp-presets#1486