Update dependency org.apache.logging.log4j:log4j-core to v2.12.4 [SECURITY] (#291)

Author: renovatebot-confluentinc[bot]

distributed-tracing/app/pom.xml

@@ -84,7 +84,7 @@
         <dependency>
             <groupId>org.apache.logging.log4j</groupId>
             <artifactId>log4j-core</artifactId>
-            <version>2.8.2</version>
+            <version>2.12.4</version>
         </dependency>
         <dependency>
             <groupId>org.apache.logging.log4j</groupId>