Add supported pluggy versions to requirements.txt (#197)
Add supported pluggy versions to requirements.txt (#197)

Because we don't have the highest supported pluggy and pytest-cov versions configured in requirements.txt,
pip installs the newest pluggy 0.7.1 which is incompatible with the pytest version we use.

For the reference see issues:
https://github.com/pytest-dev/pluggy/pull/160
https://github.com/pytest-dev/pytest/issues/3727

Solution is to add pluggy's version restrictions to our requirements.

Signed-off-by: Przemyslaw Lal <daa65d845ad9df6b8adbe544cd57021c2c7ab8ae@intel.com>
Intel-Corp/CPU-Manager-for-Kubernetes,Intel-Corp/CPU-Manager-for-Kubernetes,Intel-Corp/CPU-Manager-for-Kubernetes