Fix printing HTTP response line to stdout instead of stderr

ia-cdx-search

@@ -24,7 +24,7 @@ async def wait_first_and_print(tasks):
 		return
 	task = tasks.popleft()
 	url, code, o = await task
-	print(f'{code} {url}')
+	print(f'{code} {url}', file = sys.stderr)
 	assert o, 'got empty response'
 	fields = o[0]
 	assert all(len(v) == len(fields) for v in o[1:]), 'got unexpected response format'