fix(importer-test): typo in pubsub message (google#2702)

I noticed this typo in the pubsub messages while I was reviewing them
for another task

Author: andrewpollock

docker/importer/importer_test.py

@@ -560,8 +560,8 @@ def test_bucket(self, unused_mock_time: mock.MagicMock,
     dsa_call = mock.call(
         self.tasks_topic,
         data=b'',
-        type='test',
-        source='bucket',
+        type='update',
+        source='test',
         path='a/b/DSA-3029-1.json',
         original_sha256=mock.ANY,
         deleted='false')