Bump spring-webmvc in /s-pipes-parent

Bumps [spring-webmvc](https://github.com/spring-projects/spring-framework) from 5.0.7.RELEASE to 5.2.20.RELEASE.
- [Release notes](https://github.com/spring-projects/spring-framework/releases)
- [Commits](spring-projects/spring-framework@v5.0.7.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>

s-pipes-parent/pom.xml

@@ -20,7 +20,7 @@
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <jdk.version>1.8</jdk.version>
         <org.apache.jena>3.17.0</org.apache.jena>
-        <org.springframework.version>5.0.7.RELEASE</org.springframework.version>
+        <org.springframework.version>5.2.20.RELEASE</org.springframework.version>
         <org.springframework.security.version>5.0.6.RELEASE</org.springframework.security.version>
         <com.fasterxml.jackson.version>2.9.6</com.fasterxml.jackson.version>
         <org.eclipse.rdf4j.version>3.7.3</org.eclipse.rdf4j.version>