test email library

## Task Description
Add test for the functionality in [emailLib](https://github.com/tbf-challenge/teamwork-be/blob/main/src/lib/email-lib.js)

## Technical Considerations
1. Basically, we'll be testing the sending of an email
2. It's likely we'll be needing some kind of mocking library to mock the email sending
3. Depending on the mocking, its possible we might need some refactoring

