Fix issue with iOS purchaseProduct arguments (#957)

## Motivation

Fixes #949

## Description

There was an extra `presentedOfferingIdentifier` in the
`RCT_REMAP_METHOD` for `purchaseProduct`

Author: joshdholtz

ios/RNPurchases.m

@@ -109,7 +109,6 @@ - (dispatch_queue_t)methodQueue {
                  type:(NSString *)type
                  signedDiscountTimestamp:(NSString *)signedDiscountTimestamp
                  googleInfo:(NSDictionary *)googleInfo
-                 presentedOfferingIdentifier:(NSString *)presentedOfferingIdentifier
                  presentedOfferingContext:(NSDictionary *)presentedOfferingDictionary
                  resolve:(RCTPromiseResolveBlock)resolve
                  reject:(RCTPromiseRejectBlock)reject) {