Fix deprecation warning

Don't use the deprecated 
````
- (NSMutableURLRequest *)requestWithMethod:(NSString *)method URLString:(NSString *)URLString  parameters:(id)parameters DEPRECATED_ATTRIBUTE;
```
Instead use 
```
- (NSMutableURLRequest *)requestWithMethod:(NSString *)method URLString:(NSString *)URLString  parameters:(id)parameters error:(NSError * __autoreleasing *)error;
```