Auto-increment build version

build.gradle.kts

android {
    val versionPropsFile = file("../version.properties")

    if (versionPropsFile.canRead()) {
        val versionProps = Properties()
        versionProps.load(FileInputStream(versionPropsFile))

        val code = versionProps["VERSION_CODE"].toString().toInt() + 1
        versionProps["VERSION_CODE"] = code.toString()
        versionProps.store(versionPropsFile.writer(), null)

        defaultConfig {
            versionCode = code
        }
    } else {
        throw GradleException("Could not read version.properties!")
    }
}

version.properties

VERSION_CODE=0