flatHeights is incorrect for unicode text

[jittuu]

As below example, flatHeights and measure provide different measurement.

import TextSize from 'react-native-text-size';

const demoText = await TextSize.flatHeights({
  text: ['မြန်မာစာ'],
});

const demoSingle = await TextSize.measure({
  text: 'မြန်မာစာ',
});

// output: demoText: [17]
console.log(`demoText: ${JSON.stringify(demoText)}`);

// output: demoSingle: {"width":52.5,"lineCount":1,"height":31}
console.log(`demoSingle: ${JSON.stringify(demoSingle)}`);

The result should be 31 while flatHeights produce 17.