switching dependency from `python-hdf4` to `pyhdf`

src/setup.py

-
 from setuptools import setup, find_packages
 
 setup(name='intercal',
       version='0.1.7',
       packages=find_packages(),
       package_data={'intercal': ['*.nc']},
-      install_requires=['numpy', 'netcdf4', 'python-hdf4', 'h5py'],
+      install_requires=['numpy', 'netcdf4', 'pyhdf', 'h5py'],
       zip_safe=False,
       entry_points={'console_scripts': ['iasi_viirs=intercal.iasi_viirs:main']})