Bump ch.qos.logback:logback-classic from 1.5.20 to 1.5.21

Bumps [ch.qos.logback:logback-classic](https://github.com/qos-ch/logback) from 1.5.20 to 1.5.21.
- [Release notes](https://github.com/qos-ch/logback/releases)
- [Commits](qos-ch/logback@v_1.5.20...v_1.5.21)

---
updated-dependencies:
- dependency-name: ch.qos.logback:logback-classic
  dependency-version: 1.5.21
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

pom.xml

@@ -72,7 +72,7 @@
         <!-- Runtime dependencies (aligned with Spring Boot 3.5.7) -->
         <jackson.version>2.19.2</jackson.version>
         <slf4j.version>2.0.17</slf4j.version>
-        <logback.version>1.5.20</logback.version>
+        <logback.version>1.5.21</logback.version>
         <log4j2.version>2.24.3</log4j2.version>
         <servlet.api.version>6.0.0</servlet.api.version>