Android - Increase build number with Fastlane and Kotlin DSL

I'm trying to increase the build number of a particular variant in my android project with Fastlane.

I am using Kotlin DSL and Dev.kt for example is as follows.

object Dev: Variants {
     override val name = "DevVariant"
     override val versionCode = 7
     override val versionName = "1.2.0"
}

1- Here I want to increase the versionCode value by 1, how can I do that? 2- I also want to git commit&push this change after this operation.

Can anyone help?