feat: add vitest to testing the library

[pietrodev07]

Description:

Add Vitest as the testing framework for the library. Vitest is a fast and performant alternative to Jest, designed to work well with TypeScript and provides a modern testing experience.

Tasks:

• Install Vitest and its dependencies.
• Create a basic configuration for Vitest.
• Update the documentation with instructions on how to write and run tests using Vitest.
• Write some example tests to verify that the setup works correctly.