Update test/parallel/test-http-pipelining-no-leak.js

Co-authored-by: mscdex <[email protected]>

Author: mcollina

test/parallel/test-http-pipelining-no-leak.js

@@ -2,7 +2,7 @@
 
 const common = require('../common');
 
-// This test ensures Node.js doesn't not emit any warning when receiving
+// This test ensures Node.js doesn't emit any warnings when receiving
 // pipelined requests
 // https://github.com/nodejs/node/issues/37937