bold tags stopped working after updating to React Native 0.60.0

[prempalsingh]

Starting React Native 0.60.0, fontWeight >=500 are no longer set to bold by default.
fontWeight either needs to be set at 700 or bold for the typeface to be set as bold.

Source - https://github.com/facebook/react-native/blob/3915c0fa6178fbb8aa9b8bd54881cfdbde8fde70/ReactAndroid/src/main/java/com/facebook/react/views/text/ReactBaseTextShadowNode.java#L493

Happy to raise a PR and change the fontWeight to bold instead of 500 to fix this issue. Let me know what you think.