Fix compilation warning in test_copy_callbacks

A passed-in parameter value was incorrect, for a warning coming from
MSVC.

Oversight in 9fcdf2c.

Reported-by: Andres Freund
Discussion: https://postgr.es/m/20221011224221.dvg5q7e7vhjdtcvv@awork3.anarazel.de

src/test/modules/test_copy_callbacks/test_copy_callbacks.c

@@ -37,7 +37,7 @@ test_copy_to_callback(PG_FUNCTION_ARGS)
 	CopyToState cstate;
 	int64		processed;
 
-	cstate = BeginCopyTo(NULL, rel, NULL, RelationGetRelid(rel), NULL, NULL,
+	cstate = BeginCopyTo(NULL, rel, NULL, RelationGetRelid(rel), NULL, false,
 						 to_cb, NIL, NIL);
 	processed = DoCopyTo(cstate);
 	EndCopyTo(cstate);