double quotes to pass linting

Author: danielklim

dash/testing/application_runners.py

@@ -52,8 +52,8 @@ class BaseDashRunner(object):
     """Base context manager class for running applications."""
 
     def __init__(self, keep_open, stop_timeout):
-        self.scheme = 'http'
-        self.host = 'localhost'
+        self.scheme = "http"
+        self.host = "localhost"
         self.port = 8050
         self.started = None
         self.keep_open = keep_open