Support nested arrays in style prop

[Shywim]

What: This fixes not being able to test components which receive nested arrays in their style prop.

Why: react-native allows nested array for the style prop. Although it's not explicity written in the docs but TypeScript typings for react-native allow it and some libraries (at least react-native-paper) are making use of them.

How: We flatten the style prop before using mergeAll

Checklist:

• Documentation added to the
  docs (N/A)
• Typescript definitions updated (N/A)
• Tests
• Ready to be merged

[codecov]

Codecov Report

Merging #12 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master    #12   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           8      8           
  Lines          89     90    +1     
  Branches       23     23           
=====================================
+ Hits           89     90    +1

Impacted Files	Coverage Δ
src/to-have-style.js	100% <100%> (ø)	⬆️

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[bcarroll22]

Cool! Thanks for this!

[bcarroll22]

@allcontributors please add @Shywim for code

[allcontributors]

@bcarroll22

I've put up a pull request to add @Shywim! 🎉

[bcarroll22]

🎉 This PR is included in version 3.0.3 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀