chore(gradle): bump io.netty:netty-bom

Bumps [io.netty:netty-bom](https://github.com/netty/netty) from 4.1.127.Final to 4.2.12.Final.
- [Release notes](https://github.com/netty/netty/releases)
- [Commits](netty/netty@netty-4.1.127.Final...netty-4.2.12.Final)

---
updated-dependencies:
- dependency-name: io.netty:netty-bom
  dependency-version: 4.2.12.Final
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

gradle/libs.versions.toml

@@ -40,7 +40,7 @@ groovy = "3.0.25"
 # Only bump this in concert with netty (which will update boringssl). See the dependency matrix
 # for particular gRPC versions at https://github.com/grpc/grpc-java/blob/master/SECURITY.md#netty
 grpc = "1.76.2"
-netty = "4.1.127.Final"
+netty = "4.2.12.Final"
 
 guava = "33.4.8-jre"
 gwt = "2.12.2"