tests/basics/int_big_error.py: Use bytearray to test for int overflow.

In Python 3.7 "1 >> (big int)" is now allowed, it no longer raises an
OverflowError.  So use bytearray to test big-int conversion overflow.

tests/basics/int_big_error.py

@@ -17,9 +17,9 @@ try:
 except TypeError:
     print("TypeError")
 
-# overflow because rhs of >> is being converted to machine int
+# overflow because arg of bytearray is being converted to machine int
 try:
-    1 >> i
+    bytearray(i)
 except OverflowError:
     print('OverflowError')