fix #171 - remove warnings about deprecated hook on react 16.9.0^

[Akiyamka]

This will fix issue with warnings.
Probably will be better migrate to getDerivedStateFromProps hook with null return, but I not sure how I can call static method it this case

[eduardoborges]

Very nice ;)

[Komzpa]

Hi! Can this be merged, or is there any other thing to adjust? :)

[lkmill]

@Akiyamka hello stranger. i opened a couple of pull requests with rather substantial changes that i personally think greatly improves unistore and was looking for some feedback on. i'm assuming @developit is busy and meanwhile i was hoping to get this feedback from elsewhere. since you have opened a pull request yourself i assume you are familiar with the package and would love to hear what you think about the changes i propose. you can find them at #182 and #183. the second one builds upon the changes from the first.

[hesselbom]

@developit Any chance this could be merged? :)

[hesselbom]

For context, my reason for wanting this PR merged is because when using unistore with React Native we get this deprecation warning on every reload.

[developit]

@hesselbom ooh, that's quite the intrusive warning. I'll try to get this merged and cut a release today.

[lkmill]

@developit it was very simple to rewrite the react integration to use hooks instead and the size shrunk considerably. i have a WIP at #186

[developit]

Published as 3.5.2.