Update environment.yml for qutip 4.6
Update environment.yml for qutip 4.6

qutip4.6 requires numpy>=1.16.6,<1.20 and cython>=0.29.20

Add qutip-qip as a dependency

Pin the ipython version because there is a bug in ipykernel 5.5, see https://github.com/ipython/ipykernel/issues/540

qutip/qutip-notebooks