Bump spring-core from 4.3.18.RELEASE to 4.3.21.RELEASE in /SpringMVC

Bumps [spring-core](https://github.com/spring-projects/spring-framework) from 4.3.18.RELEASE to 4.3.21.RELEASE. - [Release notes](https://github.com/spring-projects/spring-framework/releases) - [Commits](spring-projects/spring-framework@v4.3.18.RELEASE...v4.3.21.RELEASE) --- updated-dependencies: - dependency-name: org.springframework:spring-core dependency-type: direct:production ... Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

SpringMVC/pom.xml

@@ -11,7 +11,7 @@
 
 <properties>
 <tomcat-servlet-api.version>7.0.30</tomcat-servlet-api.version>
-<spring.version>4.3.18.RELEASE</spring.version>
+<spring.version>4.3.21.RELEASE</spring.version>
 <springwebflow.version>2.3.2.RELEASE</springwebflow.version>
 <spring-security.version>4.1.1.RELEASE</spring-security.version>
 <jetty-maven-plugin.version>8.1.4.v20120524</jetty-maven-plugin.version>