Bump org.apache.logging.log4j:log4j-core in /vertx-db2-client

Bumps org.apache.logging.log4j:log4j-core from 2.20.0 to 2.25.3.

---
updated-dependencies:
- dependency-name: org.apache.logging.log4j:log4j-core
  dependency-version: 2.25.3
  dependency-type: direct:development
...

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Author: dependabot[bot]

vertx-db2-client/pom.xml

@@ -77,7 +77,7 @@
     <dependency>
       <groupId>org.apache.logging.log4j</groupId>
       <artifactId>log4j-core</artifactId>
-      <version>2.20.0</version>
+      <version>2.25.3</version>
       <scope>test</scope>
     </dependency>
     <!-- Log4j 2 SLF4J Binding -->