Tensorflow lower limit conflicts

[egpbos]

Due to the lower limit on the Tensorflow version that dianna uses, I cannot use dianna on my particular GPU setup with its particular CUDA version installed (DAS6 @ VU). This makes me sad :( Please unsad me!

It seems the change was introduced in this PR: #588. I don't see the change motivated there, but perhaps someone remembers whether there was a valid reason.

Can this be reverted? In fact, is a lower limit on Tensorflow needed at all?

[egpbos]

I see that the lower limit of 2.11 was introduced here bb42372, which does seem functional, so can we revert to 2.11?

[egpbos]

On closer look, it seems like the actual issue that bb42372 resolved was #434.

The lack of dependencies specified for tensorflow-probability are the root cause then. However, they do in fact specify the minimum required tensorflow version via an extra in setup.py. This means we can drop the upper limit and replace our dependency with tensorflow-probability[tf].

I'll make a PR for this to demonstrate (and check whether it actually works 😄).

[egpbos]

Also related: #727