Remove dup semantic rule

Author: rocky

uncompyle6/semantics/customize3.py

@@ -37,7 +37,6 @@ def customize_for_version3(self, version):
                 (0, "expr"),
                 (4, "expr"),
             ),
-            "except_cond2": ("%|except %c as %c:\n", 1, 5),
             "function_def_annotate": ("\n\n%|def %c%c\n", -1, 0),
             # When a generator is a single parameter of a function,
             # it doesn't need the surrounding parenethesis.