v2.1.0

• ✨ added the defaultWidth prop to Columns, which allows to set a default column width behavior (@domeknn)
• ✨ added the defaultHeight prop to Rows, which allows to set a default row height behavior (@domeknn)
• 🐛 fixed an issue occured in react-testing-library and react-native-web, #35
• 🐛 minor bug fixes