case-insensitive nocolor check

Author: minrk

ipyparallel/client/client.py

@@ -168,7 +168,7 @@ def _plaintext(self) -> str:
         else:
             colors = ip.colors
 
-        if colors == "NoColor":
+        if colors.lower() == "nocolor":
             out = normal = ""
         else:
             out = _TermColors.Red