Use the grading client for setting package environment

The package already have the proper setup of `requirements-qiskit.txt` and in `setup.py`. We should put this installation code inside challenges notebooks.

`pip install 'qc-grader[qiskit,jupyter] @ git+https://github.com/qiskit-community/Quantum-Challenge-Grader.git'`

There is nothing to change in this repo itself. Opening this issue to remind ourselves for the next coding challenges event.