fix: standardize requestDate to requestTime

Author: wesleyschlenker

lib/rateLimiting.js

@@ -104,7 +104,7 @@ RateLimit.parseRateLimits = function (headers) {
 RateLimit.updateRateLimits = function (headers) {
   var newLimits = this.parseRateLimits(headers)
   if (newLimits) {
-    this.requestDate = new Date()
+    this.requestTime = new Date()
     this.shortTermLimit =
       !isNaN(newLimits.shortTermLimit) ? newLimits.shortTermLimit : 0
     this.shortTermUsage =