Fix: `"null"` instead of `null` in paging.json spec (#348)

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@microsoft.azure/autorest.testserver",
-  "version": "3.2.3",
+  "version": "3.2.4",
   "description": "Autorest test server.",
   "main": "dist/cli/cli.js",
   "bin": {

swagger/paging.json

@@ -219,7 +219,7 @@
     "/paging/multiple/nextOperationWithQueryParams": {
       "get": {
         "x-ms-pageable": {
-          "nextLinkName": "null",
+          "nextLinkName": null,
           "itemName": "values"
         },
         "operationId": "Paging_nextOperationWithQueryParams",