normalize unicode in test output

for consistency on Windows, posix

nbclient/tests/test_client.py

@@ -6,6 +6,7 @@
 import os
 import re
 import threading
+import unicodedata
 import warnings
 from base64 import b64decode, b64encode
 from queue import Empty
@@ -723,11 +724,11 @@ def test_force_raise_errors(self):
             run_notebook(filename, {"force_raise_errors": True}, res)
 
         # verify CellExecutionError contents
-        exc_str = str(exc.value)
+        exc_str = unicodedata.normalize("NFC", str(exc.value))
         # print for better debugging with captured output
         # print(exc_str)
         assert "Exception: message" in exc_str
-        assert "# üñîçø∂é" in exc_str
+        assert unicodedata.normalize("NFC", "# üñîçø∂é") in exc_str
         assert "stderr" in exc_str
         assert "stdout" in exc_str
         assert "hello\n" in exc_str