fix(Checkbox): fix value prop types

[fabien0102]

Just a little fix, PropTypes doesn't match typescript definition into Checkbox.js.

// Checkbox.d.ts:79

/** The HTML input value. */
  value?: number|string;

[codecov-io]

Codecov Report

Merging #1694 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1694   +/-   ##
=======================================
  Coverage   99.75%   99.75%           
=======================================
  Files         141      141           
  Lines        2412     2412           
=======================================
  Hits         2406     2406           
  Misses          6        6

Impacted Files	Coverage Δ
src/modules/Checkbox/Checkbox.js	100% <ø> (ø)	⬆️

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[layershifter]

I fixed lint issues. LGTM, thanks for PR

[levithomason]

Released in [email protected].