feat(isPostalCode): Add CN (China) postalCode validator and test.

[httpsbao]

Hello, I add CN (China) postalCode validator and test.

Checklist

• PR contains only changes related; no stray files, etc.
• README updated (where applicable)
• Tests written (where applicable)

[codecov]

Codecov Report

Merging #1534 (727cdf0) into master (7ef0f25) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master     #1534   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           98        98           
  Lines         1763      1763           
=========================================
  Hits          1763      1763           

Impacted Files	Coverage Δ
src/lib/isPostalCode.js	100.00% <ø> (ø)

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[tux-tn]

Thank you for your contrib ! LGTM for most part 🎉
Just a little request: Can you discard your changes to auto-generated files ( index.js, validator.js and validator.min.js )

[httpsbao]

no more changes in index.js, validator.js and validator.min.js

[httpsbao]

Thank you for your contrib ! LGTM for most part 🎉
Just a little request: Can you discard your changes to auto-generated files ( index.js, validator.js and validator.min.js )

@tux-tn

Thankyou, done!

[profnandaa]

LGTM, thanks! 🎉