Switch to using black for code formatting

[manoelmarques]

Summary

Follows the changes made in Qiskit/qiskit#6361

Details and comments

[adekusar-drl]

This is a disaster! I can't say we had a very well formatted code, but this is terrible.
instead of

                    input_grad = grad_output.transpose(0, 1) @ input_grad.transpose(0, 1)

now:

                    input_grad = grad_output.transpose(0, 1) @ input_grad.transpose(
                        0, 1
                    )

Or:
instead of

                    weights_grad = weights_grad.to_dense()  # this should be eventually removed

it is

                    weights_grad = (
                        weights_grad.to_dense()
                    )  # this should be eventually removed

Or:

            parameterized_circuit = self._quantum_instance.transpile(parameterized_circuit)[0]

replaced with

            parameterized_circuit = self._quantum_instance.transpile(
                parameterized_circuit
            )[0]

and so on and so on...

[adekusar-drl]

Any ideas why max-line-length=105?

[manoelmarques]

Terra changed to 105 from 100 in their PR. I don't know why but would think it has to do on how black formatted code which may have increased de size of the code in one line.

[woodsp-ibm]

This issue in Terra has a note as to the line length of 105 Qiskit/qiskit#5883

I agree it does not do a great job in some places - I made a comment in the equivalent PR in Nature.

[adekusar-drl]

Thanks for pointing out to the Nature's PR. I agree with @mtreinish in general. Well, of course we get rid of any formatting questions but at what a cost.
I'd rather increase max line length to 140-150, we have wide screens for many years, and change the style.

[adekusar-drl]

Terra changed to 105 from 100 in their PR. I don't know why but would think it has to do on how black formatted code which may have increased de size of the code in one line.

This is the answer from Qiskit/qiskit#5883:

Black treats maximum-line-length "like a speed limit" ie if the least bad option is to exceed the line length by a little, then it will sometimes do so (I kept black using line length 100 and set the pylint/pycodestyle line length to 105 to accommodate this -- there are currently no places where this actually comes up in qiskit)