HADOOP-17614. Bump netty to the latest 4.1.61. (#2850)

Reviewed-by: Ayush Saxena <ayushsaxena@apache.org>

hadoop-project/pom.xml

@@ -139,7 +139,7 @@
     <gson.version>2.2.4</gson.version>
     <metrics.version>3.2.4</metrics.version>
     <netty3.version>3.10.6.Final</netty3.version>
-    <netty4.version>4.1.50.Final</netty4.version>
+    <netty4.version>4.1.61.Final</netty4.version>
     <snappy-java.version>1.1.8.2</snappy-java.version>
     <lz4-java.version>1.7.1</lz4-java.version>