Change source of FileFindHandler to be jupyter_server

Author: krinsman

nbviewer/app.py

@@ -43,7 +43,7 @@
 except ImportError:
     from .utils import cached_property
 
-from notebook.base.handlers import FileFindHandler as StaticFileHandler
+from jupyter_server.base.handlers import FileFindHandler as StaticFileHandler
 
 #-----------------------------------------------------------------------------
 # Code

requirements.txt

@@ -1,8 +1,8 @@
 elasticsearch
 jupyter_client
+jupyter_server>=0.2.0
 markdown>=3.0
 newrelic!=2.80.0.60
-notebook>=5.0
 nbformat>=4.2
 nbconvert>=5.4
 ipython