chore: add package bugs metadata

[mawxcodehub]

Summary

• add the package bugs.url metadata pointing to the repository issue tracker

Validation

• node -e "const p=require('./package.json'); if(p.bugs.url!=='https://github.com/stripe/react-stripe-js/issues') process.exit(1); console.log(p.name, p.bugs.url)"
• git diff --check

[cla-assistant]

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