Fix pruned txt files not being installed during pip install

MANIFEST.in

@@ -0,0 +1,2 @@
+include timm/models/pruned/*.txt
+

setup.py

@@ -41,6 +41,7 @@ setup(
     # Note that this is a string of words separated by whitespace, not a list.
     keywords='pytorch pretrained models efficientnet mobilenetv3 mnasnet',
     packages=find_packages(exclude=['convert']),
+    include_package_data=True,
     install_requires=['torch >= 1.0', 'torchvision'],
     python_requires='>=3.6',
 )