Add Netty BOM (aws-observability#1148)

*Description of changes:*
Builds are failing image scanning for `CVE-2025-55163` which recently
was added as a vulnerability.
GHSA-prj3-ccx8-p6x4

Should revert this once we upgrade our aws-sdk dependency to version
that has this PR added:
aws/aws-sdk-java-v2#6344

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 license.

---------

Co-authored-by: Thomas Pierce <[email protected]>

Author: liustve

dependencyManagement/build.gradle.kts

@@ -40,6 +40,9 @@ val dependencyBoms = listOf(
   "com.google.protobuf:protobuf-bom:3.25.1",
   "com.linecorp.armeria:armeria-bom:1.26.4",
   "io.grpc:grpc-bom:1.59.1",
+  // netty-bom is a fix for CVE-2025-55163 (https://github.com/advisories/GHSA-prj3-ccx8-p6x4).
+  // Remove once https://github.com/aws/aws-sdk-java-v2/pull/6344 is released.
+  "io.netty:netty-bom:4.1.124.Final",
   "io.opentelemetry.instrumentation:opentelemetry-instrumentation-bom-alpha:$otelAlphaVersion",
   "org.apache.logging.log4j:log4j-bom:2.21.1",
   "org.junit:junit-bom:5.10.1",