Upgrade nox (#373)

Package nox-automation is not being maintained.
Update noxfile.py syntax for new version

.travis.yml

@@ -5,7 +5,7 @@ before_install:
   - sudo apt-get -qq update
   - sudo apt-get install -y portaudio19-dev libffi-dev libssl-dev
 install:
-  - pip install nox-automation
+  - pip install nox
 script:
-  - nox -f google-assistant-grpc/nox.py -s lint
-  - nox -f google-assistant-sdk/nox.py -s lint unittest  
+  - nox -f google-assistant-grpc/noxfile.py -s lint
+  - nox -f google-assistant-sdk/noxfile.py -s lint unittest  

google-assistant-grpc/MAINTAINER.md

@@ -5,7 +5,7 @@ Maintainer guide
 
 - Install automation tools
 
-        pip install --upgrade nox-automation
+        pip install --upgrade nox
 
 ## Tasks
 

google-assistant-grpc/nox.py → google-assistant-grpc/noxfile.py

@@ -17,9 +17,8 @@
 import nox
 
 
-@nox.session
+@nox.session(python=["3"])
 def lint(session):
-    session.interpreter = 'python3'
     session.install('pip', 'setuptools')
     session.install('docutils', 'flake8', 'readme_renderer')
     session.run('flake8', 'nox.py', 'setup.py')

google-assistant-sdk/MAINTAINER.md

@@ -5,7 +5,7 @@ Maintainer guide
 
 - Install automation tools
 
-        pip install --upgrade nox-automation
+        pip install --upgrade nox
 
 ## Tasks
 

google-assistant-sdk/nox.py → google-assistant-sdk/noxfile.py

@@ -16,9 +16,8 @@
 import nox
 
 
-@nox.session
+@nox.session(python=["3"])
 def lint(session):
-    session.interpreter = 'python3'
     session.install('pip', 'setuptools')
     session.install('docutils', 'flake8', 'readme_renderer')
     session.run('flake8',
@@ -29,21 +28,17 @@ def lint(session):
     session.run('python', '-m', 'json.tool', 'actions.json')
 
 
-@nox.session
-@nox.parametrize('python_version', ['2.7', '3'])
-def unittest(session, python_version):
-    session.interpreter = 'python' + python_version
+@nox.session(python=['2.7', '3'])
+def unittest(session):
     session.install('pip', 'setuptools')
     session.install('pytest', 'future')
     session.install('../google-assistant-grpc/')
     session.install('-e', '.[samples]')
     session.run('py.test', '-k', 'not test_endtoend', 'tests')
 
 
-@nox.session
-@nox.parametrize('python_version', ['2.7', '3'])
-def endtoend_test(session, python_version):
-    session.interpreter = 'python' + python_version
+@nox.session(python=['2.7', '3'])
+def endtoend_test(session):
     session.install('pip', 'setuptools')
     session.install('pytest', 'future')
     session.install('../google-assistant-grpc/')