Add minimal versions and licensing information for requirements

Requirements should clearly state their license as this aids in resolving potential licensing conflicts much more easily.

In addition, these requirements should denote a minimal version based on the features they need from these requirements.

Afterwards, these minimal versions can be extended with a lower-constraints job which verifies that all minimal versions results in a functional application.

tests/requirements.txt

-black
-build
-flake8
 autopep8 >= 1.7.0 # MIT
-pylint
-pytest
-pytest-cov
+black >= 22.0.0 # MIT
+build >= 0.8.0 # MIT
+flake8 >= 5.0.0 # MIT
+pylint >= 2.15.0 # GPLv2
+pytest >= 7.0.0 # MIT
+pytest-cov >= 3.0.0 # MIT