tests/basics: Use bytes not bytearray when checking user buffer proto.

Using bytes will test the same path for the buffer protocol in
py/objtype.c.

tests/basics/class_misc.py

@@ -4,6 +4,6 @@ class C:
 
 c = C()
 try:
-    d = bytearray(c)
+    d = bytes(c)
 except TypeError:
     print('TypeError')