Add `install: requirements` section to .readthedocs.yml (#1969)
Add `install: requirements` section to .readthedocs.yml (#1969)

Fixes: https://github.com/quantumlib/Cirq/issues/1204
balopat/Cirq,balopat/Cirq,quantumlib/Cirq,balopat/Cirq,quantumlib/Cirq,quantumlib/Cirq,quantumlib/Cirq,quantumlib/Cirq