gplazma2: fix junit assert deprecation warnings

Motivation:
The JUnit Assert class was moved to a different package in version 4, leading to deprecation warnings when importing from the old one.

Modification:
Update the Assert import path where the old one is still used.

Result:
Fewer deprecation warnings regarding JUnit.

Target: master
Requires-notes: no
Requires-book: no
Patch: https://rb.dcache.org/r/13441/
Acked-by: Paul Millar

modules/gplazma2-grid/src/test/java/org/dcache/gplazma/plugins/CachedVOMapTest.java

@@ -1,7 +1,7 @@
 package org.dcache.gplazma.plugins;
 
-import static junit.framework.Assert.assertEquals;
-import static junit.framework.Assert.assertTrue;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
 
 import com.google.common.collect.Lists;
 import com.google.common.io.Resources;

modules/gplazma2/src/test/java/org/dcache/gplazma/loader/XmlResourcePluginLoaderTests.java

@@ -4,8 +4,8 @@
 
 import java.util.Collections;
 import java.util.Properties;
-import junit.framework.Assert;
 import org.dcache.gplazma.plugins.GPlazmaPlugin;
+import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;