test: convert callback to arrow function

PR-URL: https://github.com/nodejs/node/pull/24513
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

test/pummel/test-net-pause.js

@@ -45,7 +45,7 @@ const server = net.createServer((connection) => {
 server.on('listening', () => {
   const client = net.createConnection(common.PORT);
   client.setEncoding('ascii');
-  client.on('data', function(d) {
+  client.on('data', (d) => {
     console.log(d);
     recv += d;
   });