Fix test_collections

Author: slozier

src/core/IronPython.StdLib/lib/collections/__init__.py

@@ -1193,6 +1193,7 @@ def index(self, sub, start=0, end=_sys.maxsize):
         return self.data.index(sub, start, end)
     def isalpha(self): return self.data.isalpha()
     def isalnum(self): return self.data.isalnum()
+    def isascii(self): return self.data.isascii() # ironpython: we added str.isascii, make test_collections happy
     def isdecimal(self): return self.data.isdecimal()
     def isdigit(self): return self.data.isdigit()
     def isidentifier(self): return self.data.isidentifier()