Update to use latest version of Cirq

[mhucka]

Cirq 1.4.x has been out for a while, and we should update to it. If 1.5.0 comes out before we release TFQ 0.7.4, we should support that.

[Kerbeccs]

Hi @mhucka, I'd like to contribute to this issue. I see it's targeting Release 0.8.0. Which Cirq version should I target — 1.5.x or something newer? Also, is anyone actively working on this? Happy to pick it up if not.

[mhucka]

@Kerbeccs Thanks for your interest.

Ideally we would want to support the latest version of Cirq; however, this is tricky because of the tangled dependencies between TensorFlow, TensorFlow Quantum, Keras, Cirq, qsim, and their transitive dependencies, and also because later versions of Cirq dropped support for Python 3.10 whereas TFQ still tries to support it. Let me work first on getting #1051 merged because that's going to change a bunch of dependency versions. Then we can assess the implications of raising Cirq's version.

[Kerbeccs]

Makes complete sense, thanks for the heads up! I'll keep an eye on #1051. Once that's merged and the team has decided how to handle the Python 3.10 / Cirq versioning, let me know — I'm still happy to help tackle the update