Bump org.apache.logging.log4j:log4j-bom from 2.20.0 to 2.21.1 in /java (aws-observability#979)

Bumps [org.apache.logging.log4j:log4j-bom](https://github.com/apache/logging-log4j2) from 2.20.0 to 2.21.1.
- [Release notes](https://github.com/apache/logging-log4j2/releases)
- [Commits](apache/logging-log4j2@rel/2.20.0...rel/2.21.1)

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

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Author: dependabot[bot]

java/dependencyManagement/build.gradle.kts

@@ -10,7 +10,7 @@ data class DependencySet(val group: String, val version: String, val modules: Li
 
 val DEPENDENCY_BOMS = listOf(
     "io.opentelemetry.instrumentation:opentelemetry-instrumentation-bom-alpha:1.31.0-alpha",
-    "org.apache.logging.log4j:log4j-bom:2.20.0",
+    "org.apache.logging.log4j:log4j-bom:2.21.1",
     "software.amazon.awssdk:bom:2.21.0"
 )