increase android build number

android {
    compileSdkVersion rootProject.ext.compileSdkVersion

    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }

    def versionPropsFile = file('version.properties')
    def code

    if (versionPropsFile.canRead()) {
        def Properties versionProps = new Properties()

        versionProps.load(new FileInputStream(versionPropsFile))

        code = versionProps['VERSION_CODE'].toInteger() + 1

        if (System.getenv('BUMP_VERSION') == 'yes') {
          versionProps['VERSION_CODE']=code.toString()
          versionProps.store(versionPropsFile.newWriter(), null)
        }
    } else {
        throw new GradleException("Could not read version.properties!")
    }

    defaultConfig {
        versionCode 1
        applicationId "co.petpit.petpit"
        minSdkVersion rootProject.ext.minSdkVersion
        targetSdkVersion rootProject.ext.targetSdkVersion
        versionName "1.0.2"
        multiDexEnabled true
    }
...