Fix mockito imports

Signed-off-by: Álvaro Brey Vilas <alvaro.brey@nextcloud.com>

src/test/java/com/owncloud/android/ui/activities/ActivitiesPresenterTest.java

@@ -35,7 +35,7 @@ import org.mockito.MockitoAnnotations;
 import java.util.ArrayList;
 import java.util.List;
 
-import static org.mockito.Matchers.eq;
+import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.verify;
 
 public class ActivitiesPresenterTest {

src/test/java/com/owncloud/android/ui/activities/data/activities/RemoteActivitiesRepositoryTest.java

@@ -30,7 +30,7 @@ import org.mockito.MockitoAnnotations;
 import java.util.ArrayList;
 import java.util.List;
 
-import static org.mockito.Matchers.eq;
+import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.verify;
 
 public class RemoteActivitiesRepositoryTest {

src/test/java/com/owncloud/android/ui/activities/data/files/RemoteFilesRepositoryTest.java

@@ -28,7 +28,7 @@ import org.mockito.Captor;
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 
-import static org.mockito.Matchers.eq;
+import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.verify;
 
 public class RemoteFilesRepositoryTest {