Update netty monorepo to v4.2.9.Final

Author: renovate[bot]

gradle/libs.versions.toml

@@ -18,7 +18,7 @@ adventure = "4.25.0"
 adventure-platform-bukkit = "4.4.1"
 
 # External
-netty = "4.2.7.Final"
+netty = "4.2.9.Final"
 
 [libraries]
 kotlin-stdlib = { module = "org.jetbrains.kotlin:kotlin-stdlib-jdk8", version.ref = "kotlin"}