Migration to munit

[nikololiahim]

munit is a unit testing framework for Scala. Its advantages, among other things, are :

• clearer and much more informative error messages (esp. when it comes to scalacheck failures)
• a more seamless integration with both cats-effect and scalacheck (less .unsafeRunSync() moments)
• much less dependencies: scalatest is 33 artifacts, whereas munit - only 5.

Disadvantages:

• Does not support concurrent execution of test cases within a test suite. Test suites are still executed concurrently.