Switch to JUnit 4 assumptions

Author: ppkarwasz

log4j-core-test/src/test/java/org/apache/logging/log4j/core/appender/rolling/RollingAppenderRestartTest.java

@@ -20,9 +20,9 @@
 import static org.apache.logging.log4j.core.test.hamcrest.FileMatchers.hasName;
 import static org.hamcrest.Matchers.endsWith;
 import static org.hamcrest.Matchers.hasItemInArray;
-import static org.junit.jupiter.api.Assertions.assertNotNull;
-import static org.junit.jupiter.api.Assertions.assertTrue;
-import static org.junit.jupiter.api.Assumptions.assumeTrue;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assume.assumeTrue;
 
 import java.io.File;
 import java.io.IOException;