remove unused import

Author: Vladimir Kotal

opengrok-indexer/src/main/java/org/opengrok/indexer/index/Indexer.java

@@ -35,7 +35,6 @@
 import java.lang.reflect.InvocationTargetException;
 import java.net.URI;
 import java.net.URISyntaxException;
-import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;