Please follow the steps!
Step 1 – Open your project folder android/app/build.gradle and under defaultConfig update versionCode and versionName
defaultConfig {
applicationId "com.austroapp"
minSdkVersion rootProject.ext.minSdkVersion
targetSdkVersion rootProject.ext.targetSdkVersion
versionCode 2
versionName "2.0"
}
Increment your previous versionCode and versionName by 1.