Bump io.netty:netty-all from 4.0.56.Final to 4.2.15.Final

Bumps [io.netty:netty-all](https://github.com/netty/netty) from 4.0.56.Final to 4.2.15.Final.
- [Release notes](https://github.com/netty/netty/releases)
- [Commits](netty/netty@netty-4.0.56.Final...netty-4.2.15.Final)

---
updated-dependencies:
- dependency-name: io.netty:netty-all
  dependency-version: 4.2.15.Final
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

mr/build.gradle

@@ -65,7 +65,7 @@ dependencies {
 
     testImplementation(project(":test:shared"))
     testImplementation("com.fasterxml.jackson.core:jackson-databind:2.21.3")
-    testImplementation("io.netty:netty-all:4.2.10.Final")
+    testImplementation("io.netty:netty-all:4.2.15.Final")
     testImplementation("org.elasticsearch:securemock:1.2")
 
     itestEmbedded(project(":test:shared"))

test/shared/build.gradle

@@ -80,7 +80,7 @@ dependencies {
 
     implementation("org.hamcrest:hamcrest-all:${project.ext.hamcrestVersion}")
 
-    implementation("io.netty:netty-all:4.0.56.Final") {
+    implementation("io.netty:netty-all:4.2.15.Final") {
         because "Needed for creating mock SSL Server to test against"
     }