Manifest merger failed : uses-sdk:minSdkVersion 20 cannot be smaller than version 21 declared in library [:stringee_flutter_plugin] ../build/stringee_flutter_plugin/intermediates/merged_manifest/release/AndroidManifest.xml as the library might be using APIs not available in 20
Suggestion: use a compatible library with a minSdk of at most 20,
or increase this project's minSdk version to at least 21,