Update log4j to non-vulnerable versions (#511)

Author: Alphadelta14

custom_model_runner/datarobot_drum/drum/language_predictors/java_predictor/pom.xml

@@ -34,7 +34,7 @@
         <dependency>
             <groupId>org.apache.logging.log4j</groupId>
             <artifactId>log4j-core</artifactId>
-            <version>2.14.1</version>
+            <version>2.15.0</version>
         </dependency>
 
        <!-- https://mvnrepository.com/artifact/ai.h2o/h2o-genmodel -->
@@ -121,4 +121,4 @@
             </build>
         </profile>
     </profiles>
-</project>
+</project>