Bump org.apache.logging.log4j:log4j-bom in /data-prepper-expression (#6896)

Bumps [org.apache.logging.log4j:log4j-bom](https://github.com/apache/logging-log4j2) from 2.25.3 to 2.26.0.
- [Release notes](https://github.com/apache/logging-log4j2/releases)
- [Changelog](https://github.com/apache/logging-log4j2/blob/2.x/RELEASE-NOTES.adoc)
- [Commits](apache/logging-log4j2@rel/2.25.3...rel/2.26.0)

---
updated-dependencies:
- dependency-name: org.apache.logging.log4j:log4j-bom
  dependency-version: 2.26.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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data-prepper-expression/build.gradle

@@ -28,7 +28,7 @@ dependencies {
     implementation(libs.spring.context) {
         exclude group: 'commons-logging', module: 'commons-logging'
     }
-    implementation platform('org.apache.logging.log4j:log4j-bom:2.25.3')
+    implementation platform('org.apache.logging.log4j:log4j-bom:2.26.0')
     implementation 'org.apache.logging.log4j:log4j-core'
     implementation 'org.apache.logging.log4j:log4j-slf4j2-impl'
     implementation 'com.github.seancfoley:ipaddress:5.5.1'