Update Mockito version

src/test/java/fr/xephi/authme/permission/PermissionsManagerTest.java

@@ -8,7 +8,7 @@ import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.mockito.InjectMocks;
 import org.mockito.Mock;
-import org.mockito.runners.MockitoJUnitRunner;
+import org.mockito.junit.MockitoJUnitRunner;
 
 import static org.hamcrest.Matchers.equalTo;
 import static org.junit.Assert.assertThat;