fix comments

Author: przemkaczmarek

src/test/java/org/prebid/server/bidder/alliancegravity/AllianceGravityBidderTest.java

@@ -31,9 +31,8 @@
 import java.util.function.UnaryOperator;
 
 import static java.util.Collections.singletonList;
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
-import static org.prebid.server.assertion.FutureAssertion.assertThat;
-
 public class AllianceGravityBidderTest extends VertxTest {
 
     private static final String ENDPOINT_URL = "https://test.endpoint.com/";