Need to add support for new Context API

[viktor-equinix]

react-redux@6 moved to new Context API and now using redux-modal we have warning about missing store in context.

[yesmeck]

@viktor-equinix Could you open a PR?

[matthewlilley]

@viktor-equinix Leaving this here for reference. If I get a chance, I'll make a PR.

https://github.com/reduxjs/react-redux/releases/tag/v6.0.0

[cozmy]

@viktor-equinix Could you open a PR?

I could. The changes are very minimal. But somehow, I'm breaking your TS build :(
Besides the update to react-redux v6, this is all that's needed:

[yesmeck]

@cozmy We need a major version release.

[yesmeck]

Released https://github.com/yesmeck/redux-modal/releases/tag/3.0.0