Update broken PropTypes

[arielwb]

Hello!

I was trying to use your package, but it throws an arror on import.
I dig a little the source code, and in fact, you are trying to use PropTypes from react,
but sinse v15.5 it has moved:

Note:
React.PropTypes has moved into a different package since React v15.5. Please use the prop-types library instead.
We provide a codemod script to automate the conversion.

source: https://reactjs.org/docs/typechecking-with-proptypes.html

;))

[josiahstapleton]

Same issue here. Is this package still maintained?