fix: invalid case on writeconcern makes skip check fail (#2773)

Author: unusualbob

lib/operations/connect.js

@@ -569,7 +569,7 @@ function createUnifiedOptions(finalOptions, options) {
     'mongos_options'
   ];
   const noMerge = ['readconcern', 'compression', 'autoencryption'];
-  const skip = ['w', 'wtimeout', 'j', 'journal', 'fsync', 'writeConcern'];
+  const skip = ['w', 'wtimeout', 'j', 'journal', 'fsync', 'writeconcern'];
 
   for (const name in options) {
     if (skip.indexOf(name.toLowerCase()) !== -1) {