upgrade json-schema-validator to 1.0.20

Author: stevehu

pom.xml

@@ -84,7 +84,7 @@
         <java.version>1.8</java.version>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <version.light-4j>1.6.9-SNAPSHOT</version.light-4j>
-        <version.json-schema-validator>1.0.19</version.json-schema-validator>
+        <version.json-schema-validator>1.0.20</version.json-schema-validator>
         <version.jackson>2.9.9</version.jackson>
         <version.jackson-databind>2.9.9.3</version.jackson-databind>
         <version.slf4j>1.7.25</version.slf4j>