Ensure that mkl_fft/tests are included in the layout

Author: oleksandr-pavlyk

setup.py

@@ -120,6 +120,7 @@ def extensions():
         "mkl_fft",
         "mkl_fft.interfaces",
     ],
+    package_data={"mkl_fft": ["tests/*.py"]},
     include_package_data=True,
     ext_modules=extensions(),
     zip_safe=False,