Fix JUnit5 migration (#954)

Author: strangelookingnerd

src/test/java/io/jenkins/plugins/pipelinegraphview/utils/PipelineNodeUtilTest.java

@@ -2,8 +2,8 @@
 
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.*;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import hudson.model.Result;
 import io.jenkins.plugins.pipelinegraphview.treescanner.PipelineNodeGraphAdapter;