build: upgrade json-migration-helper to 0.9.1

Author: javier-godoy

pom.xml

@@ -128,7 +128,7 @@
         <dependency>
             <groupId>com.flowingcode.vaadin</groupId>
             <artifactId>json-migration-helper</artifactId>
-            <version>0.9.0</version>
+            <version>0.9.1</version>
         </dependency>
         <dependency>
               <groupId>org.ow2.asm</groupId>