Upgrade to Spring 4.3.21.RELEASE

Fixes gh-339

Author: kazuki43zoo

pom.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!--
 
-       Copyright 2010-2018 the original author or authors.
+       Copyright 2010-2019 the original author or authors.
 
        Licensed under the Apache License, Version 2.0 (the "License");
        you may not use this file except in compliance with the License.
@@ -105,7 +105,7 @@
     <gcu.product>Spring</gcu.product>
     <osgi.import>org.springframework.batch.*;resolution:=optional,*</osgi.import>
     <osgi.dynamicImport>*</osgi.dynamicImport>
-    <spring.version>4.3.20.RELEASE</spring.version>
+    <spring.version>4.3.21.RELEASE</spring.version>
   </properties>
 
   <dependencies>