Some dependencies are incorrect/unnecessary #159
Description
sklearnis declared as a dependency here. But this should likely bescikit-learn. Also it does not appear to be used anywhere in the actual ffcv source.matplotlibis declared as a dependency here but does not appear to be used anywhere in the actual ffcv source.fastargsis declared as a dependency here but is only used in the cifar example code.imgcatis declared as a dependency here but is not used in the actual ffcv source.assertpyis declared as a dependency here but is only used in the tests and benchmarks.psutilis declared as a dependency here but is only used in the tests.webdatasetis declared as a dependency here, but is identified as optional in the code.