[BUGFIX] Include turbulence_intensities in turbine_previewer.py

[misi9170]

When merging #888 , the deployment of the documentation failed because one of the documentation notebooks calls methods on the TurbineInterface class, which I had missed when passing the turbulence_intensities keyword argument to calls to power() and thrust_coefficient(). This fixes that problem.

Perhaps a bigger issue is that TurbineInterface does not seem to be covered by tests and examples (it is only used in the documentation). I've opened #901 to discuss.

Note that here, for simplicity, I'm passing 0 in for turbulence_intensities. That works, for now, because turbulence intensity is anyway not used in most operation models. However, if in future we expand the usage of the TurbineInterface class to be more broadly compatible with operation models, we may want to add turbulence_intensities as an input to some of the methods (so that, if an operation model whose output depends on the turbulence intensity is used, that dependency can be demonstrated).