fix(deps): update dependency ch.qos.logback:logback-classic to v1.5.21 (#885)

This PR contains the following updates:

| Package | Change | Age | Confidence |
|---|---|---|---|
| [ch.qos.logback:logback-classic](http://logback.qos.ch)
([source](https://redirect.github.com/qos-ch/logback),
[changelog](https://logback.qos.ch/news.html)) | `1.5.20` -> `1.5.21` |
[![age](https://developer.mend.io/api/mc/badges/age/maven/ch.qos.logback:logback-classic/1.5.21?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![confidence](https://developer.mend.io/api/mc/badges/confidence/maven/ch.qos.logback:logback-classic/1.5.20/1.5.21?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|

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generator/pom.xml

@@ -120,7 +120,7 @@
         <dependency>
             <groupId>ch.qos.logback</groupId>
             <artifactId>logback-classic</artifactId>
-            <version>1.5.20</version>
+            <version>1.5.21</version>
         </dependency>
     </dependencies>
     <properties>