Remove unnecessary import

Author: alcaeus

tests/Operation/WatchFunctionalTest.php

@@ -16,7 +16,6 @@
 use MongoDB\Driver\ReadPreference;
 use MongoDB\Driver\WriteConcern;
 use MongoDB\Exception\ResumeTokenException;
-use MongoDB\Operation\DatabaseCommand;
 use MongoDB\Operation\InsertOne;
 use MongoDB\Operation\Watch;
 use MongoDB\Tests\CommandObserver;