fix: export issue

[gavinr]

json-to-csv switched to promises in v4, so we had to update where we were using that here.

resolves #101

[github-actions[bot]]

:tada: This PR is included in version 3.1.8 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: