Bump org.apache.logging.log4j:log4j-core in /backend

Bumps org.apache.logging.log4j:log4j-core from 2.25.3 to 2.25.4.

---
updated-dependencies:
- dependency-name: org.apache.logging.log4j:log4j-core
  dependency-version: 2.25.4
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

backend/pom.xml

@@ -60,7 +60,7 @@
         <dependency>
             <groupId>org.apache.logging.log4j</groupId>
             <artifactId>log4j-core</artifactId>
-            <version>2.25.3</version>
+            <version>2.25.4</version>
         </dependency>
         <dependency>
             <groupId>commons-io</groupId>