Bump org.simplify4u:parent from 2.20.0 to 2.21.0

Bumps [org.simplify4u:parent](https://github.com/s4u/parent) from 2.20.0 to 2.21.0.
- [Release notes](https://github.com/s4u/parent/releases)
- [Commits](s4u/parent@v2.20.0...v2.21.0)

---
updated-dependencies:
- dependency-name: org.simplify4u:parent
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

pom.xml

@@ -21,7 +21,7 @@
     <parent>
         <groupId>org.simplify4u</groupId>
         <artifactId>parent</artifactId>
-        <version>2.20.0</version>
+        <version>2.21.0</version>
     </parent>
 
     <artifactId>slf4j-mock-parent</artifactId>