feat(isMobilePhone): Added regex for Mongolia mn-MN

[rksp25]

Added regex for Mongolia mn-MN

Checklist

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

[codecov]

Codecov Report

Merging #1993 (61ee147) into master (cfcf911) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master     #1993   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          103       103           
  Lines         2097      2097           
  Branches       473       473           
=========================================
  Hits          2097      2097           

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

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[profnandaa]

Thanks for your contrib on this. This is the very first mn-Mn locale one, you could also do more others!

[profnandaa]

LGTM

[rksp25]

Hi @profnandaa i have raised one more for country BENIN: #1997