fix(types): allow string fail_existing for customers.create

[Sayansh2004]

Summary

Updates the TypeScript type for fail_existing on customer create so callers can use string '0' / '1' in addition to boolean and numeric 0 / 1, which matches what the Customers API accepts (see #463).

Changes

• lib/types/customers.d.ts: widen fail_existing and clarify JSDoc.
• dist/types/customers.d.ts: synced from lib after build.
• CHANGELOG.md: Unreleased note under the same style as previous entries.

Testing

• Ran npm test locally (build + mocha + nyc); all tests passed.
• Confirmed in TypeScript that customers.create({ ..., fail_existing: '0' }) and fail_existing: '1' type-check without errors.

Fixes #463

[Sayansh2004]

Summary

Updates the TypeScript type for fail_existing on customer create so callers can use string '0' / '1' in addition to boolean and numeric 0 / 1, which matches what the Customers API accepts (see #463).

Changes

• lib/types/customers.d.ts: widen fail_existing and clarify JSDoc.
• dist/types/customers.d.ts: synced from lib after build.
• CHANGELOG.md: Unreleased note under the same style as previous entries.

Testing

• Ran npm test locally (build + mocha + nyc); all tests passed.
• Confirmed in TypeScript that customers.create({ ..., fail_existing: '0' }) and fail_existing: '1' type-check without errors.

Fixes #463

Hi — the BVT check asks for the Tested (with test doc) or TestingNotRequired label. This PR only updates TypeScript types and CHANGELOG for #463. Could a maintainer please add TestingNotRequired, and approve the pending workflows if needed? Thanks.

[Sayansh2004]

Hi — the BVT check asks for the Tested (with test doc) or TestingNotRequired label. This PR only updates TypeScript types and CHANGELOG for #463. Could a maintainer please add TestingNotRequired, and approve the pending workflows if needed? Thanks.