fix running the curses.has_key module (closes bpo-33359) (GH-6608)

This was broken by poor automated translation back in 6e3dbbdf39f3b4eb6f18c0165e446df17218b7dc.
diff --git a/Lib/curses/has_key.py b/Lib/curses/has_key.py
index 1dd5a3b..60b7be9 100644
--- a/Lib/curses/has_key.py
+++ b/Lib/curses/has_key.py
@@ -182,7 +182,7 @@
         L = []
         _curses.initscr()
         for key in _capability_names.keys():
-            system = key in _curses
+            system = _curses.has_key(key)
             python = has_key(key)
             if system != python:
                 L.append( 'Mismatch for key %s, system=%i, Python=%i'