Expand Python version compatibility

[pedrorrivero]

Is your feature request related to a problem? Please describe.

Currently, QRAND can only be installed for Python >= 3.9.

Describe the solution you'd like

QRAND should work with Python versions >=:

• 3.8
• 3.7

Additional context

The reason why Python 3.9 was used initially is that previous version seemed to be unstable when interfaced with Qiskit.