chore(package): update enzyme

[layershifter]

This PR updates enzyme and enzyme-adapter-react-16, they have correct support of Fragment and forwardRef APIs.

[codecov]

Codecov Report

Merging #492 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #492   +/-   ##
=======================================
  Coverage   88.41%   88.41%           
=======================================
  Files          42       42           
  Lines        1450     1450           
  Branches      211      211           
=======================================
  Hits         1282     1282           
  Misses        163      163           
  Partials        5        5

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[layershifter]

This argument is options, null and undefined aren't equal for default args:

function getValue(value = { foo: 'bar' }) {
  return value
}

console.log(getValue(null)) // => null
console.log(getValue(undefined)) // {foo: "bar"}

[kuzhelov]

great catch!