Fix #488: update ion-java dep to 1.11.7 (#489)

Author: tgregg

ion/pom.xml

@@ -39,7 +39,7 @@ tree model)
     <dependency>
       <groupId>com.amazon.ion</groupId>
       <artifactId>ion-java</artifactId>
-      <version>1.11.4</version>
+      <version>1.11.7</version>
     </dependency>
 
     <!-- Extends Jackson core, databind -->