Bump system-stubs.version from 2.0.2 to 2.1.3

Bumps `system-stubs.version` from 2.0.2 to 2.1.3.

Updates `uk.org.webcompere:system-stubs-core` from 2.0.2 to 2.1.3
- [Release notes](https://github.com/webcompere/system-stubs/releases)
- [Changelog](https://github.com/webcompere/system-stubs/blob/main/History.md)
- [Commits](webcompere/system-stubs@system-stubs-parent-2.0.2...system-stubs-parent-2.1.3)

Updates `uk.org.webcompere:system-stubs-jupiter` from 2.0.2 to 2.1.3
- [Release notes](https://github.com/webcompere/system-stubs/releases)
- [Changelog](https://github.com/webcompere/system-stubs/blob/main/History.md)
- [Commits](webcompere/system-stubs@system-stubs-parent-2.0.2...system-stubs-parent-2.1.3)

---
updated-dependencies:
- dependency-name: uk.org.webcompere:system-stubs-core
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: uk.org.webcompere:system-stubs-jupiter
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

log4j-parent/pom.xml

@@ -141,7 +141,7 @@
     <slf4j.version>1.7.36</slf4j.version>
     <spring-boot.version>2.7.15</spring-boot.version>
     <spring-framework.version>5.3.30</spring-framework.version>
-    <system-stubs.version>2.0.2</system-stubs.version>
+    <system-stubs.version>2.1.3</system-stubs.version>
     <tomcat-juli.version>10.0.27</tomcat-juli.version>
     <velocity.version>1.7</velocity.version>
     <wiremock.version>2.35.1</wiremock.version>