Fixed vulnerabilities present in the "jsonwebtoken" library

Updated jsonwebtoken from version 8.5 to 9.
All tests passed.

API security best practices and Unit Testing

This new release includes:

• 100% unit testing coverage
• Limit in the number of calls per API made to the SignUp route
• Delay in the calls response after a certain number of calls made to the SignUp route
• Readme updates

v1.0.1 Initial features

This version includes User/Password authentication and JWT token authorization