Release 0.8.1 to fix pypi issues

gym-unity/setup.py

       author_email='ML-Agents@unity3d.com',
       url='https://github.com/Unity-Technologies/ml-agents',
       packages=find_packages(),
-      install_requires=['gym', 'mlagents_envs==0.8.0']
+      install_requires=['gym', 'mlagents_envs==0.8.1']
       )

ml-agents-envs/setup.py

 
 setup(
     name='mlagents_envs',
-    version='0.8.0',
+    version='0.8.1',
     description='Unity Machine Learning Agents Interface',
     url='https://github.com/Unity-Technologies/ml-agents',
     author='Unity Technologies',

ml-agents/setup.py

 
 setup(
     name='mlagents',
-    version='0.8.0',
+    version='0.8.1',
     description='Unity Machine Learning Agents',
     long_description=long_description,
     long_description_content_type='text/markdown',
     zip_safe=False,
 
     install_requires=[
-        'mlagents_envs==0.8.0',
+        'mlagents_envs==0.8.1',
         'tensorflow>=1.7,<1.8',
         'Pillow>=4.2.1',
         'matplotlib',