Update ASM to 6.1 in order to support Java 10 class format

Author: plamentotev

plexus-java/pom.xml

@@ -39,7 +39,7 @@
     <dependency>
       <groupId>org.ow2.asm</groupId>
       <artifactId>asm</artifactId>
-      <version>6.0</version>
+      <version>6.1</version>
     </dependency>
     <dependency>
       <groupId>com.thoughtworks.qdox</groupId>