read config using utf-8

Author: casperdcl

nbval/plugin.py

@@ -284,7 +284,7 @@ def setup_sanitize_files(self):
         load the contents of the file into the sanitise patterns dictionary.
         """
         for fname in self.get_sanitize_files():
-            with open(fname, 'r') as f:
+            with open(fname, 'r', encoding="utf-8") as f:
                 self.sanitize_patterns.update(get_sanitize_patterns(f.read()))