Added isTaxID implementation, test cases and updated readme for 'en-IN'

[ajinkyac03]

• Added TIN validation for India('en-IN') i.e PAN(Permanent Account Number)
• Resolves #2030

Checklist

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

[codecov[bot]]

Codecov Report

Merging #2032 (8502d26) into master (86a07ba) will not change coverage. The diff coverage is n/a.

@@            Coverage Diff            @@
##            master     #2032   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          104       104           
  Lines         2203      2203           
  Branches       477       477           
=========================================
  Hits          2203      2203           

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

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

[ajinkyac03]

@braaar anything more needed from my end?

[braaar]

No, I don't think so. We just have to wait for maintainer review.