Update Gradle wrapper v4 to latest

Hi,
I have just noticed that the project is using gradle version 4 which is like really old, so I am creating this issue to request an update to the latest Gradle version (Gradle 8.13 at the moment) so this project can be developed further with modern Gradle API.
This may require some adjustments in build.gradle.

Not sure who you are requesting that from, but feel free to submit a pull request with such an update.