remove unused import

Author: Vladimir Kotal

opengrok-indexer/src/test/java/org/opengrok/indexer/history/GitRepositoryTest.java

@@ -28,7 +28,6 @@
 import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
-import java.nio.file.Files;
 import java.nio.file.Paths;
 import java.text.ParseException;
 import java.util.Arrays;