Bump spring-webmvc in /spring_controller

Bumps [spring-webmvc](https://github.com/spring-projects/spring-framework) from 5.1.4.RELEASE to 5.2.20.RELEASE.
- [Release notes](https://github.com/spring-projects/spring-framework/releases)
- [Commits](spring-projects/spring-framework@v5.1.4.RELEASE...v5.2.20.RELEASE)

---
updated-dependencies:
- dependency-name: org.springframework:spring-webmvc
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

spring_controller/pom.xml

@@ -23,7 +23,7 @@
     <java.web.api.version>8.0</java.web.api.version>
 
     <!-- Spring -->
-    <spring.version>5.3.16</spring.version>
+    <spring.version>5.3.18</spring.version>
 
     <!-- Other stuff dependencies -->
     <jackson.version>2.11.2</jackson.version>