Allow Notebook 6.x dependencies (#321)

Author: juliusvonkohout

requirements.txt

@@ -1,6 +1,6 @@
 jupyter_core>=4.4.0
 jupyter_client>=5.2.0
-notebook>=5.7.6,<6.0
+notebook>=5.7.6,<7.0
 traitlets>=4.2.0
 tornado>=4.2.0
 requests>=2.7,<3.0

setup.py

@@ -55,7 +55,7 @@
     install_requires=[
         'jupyter_core>=4.4.0',
         'jupyter_client>=5.2.0',
-        'notebook>=5.7.6,<6.0',
+        'notebook>=5.7.6,<7.0',
         'traitlets>=4.2.0',
         'tornado>=4.2.0',
         'requests>=2.7,<3.0'