gwskynet unit test fails with new tensorflow release

Our CI tests that use bleeding edge dependencies started failing after the latest release of tensorflow. The gwskynet unit test throws complains TypeError: Could not locate class 'Functional'. followed by a very long message. An example of a failed job can be seen here. Pinning tensorflow-cpu < 2.16 fixes the issue, but we should drop that pin once it's fixed on gwskynet's end.