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')

tests/basics/subclass_native_buffer.py

@@ -12,5 +12,5 @@ print(b1 + b2)
 print(b1 + b3)
 print(b3 + b1)
 
-# bytearray construction will use the buffer protocol
-print(bytearray(b1))
+# bytes construction will use the buffer protocol
+print(bytes(b1))