Resolve #722 "iOS Release network requests not completing"

[teodorciuraru]

Providing the third, less intrusive, solution as discussed in #722 and refers to making a minor modification that proved to work for us locally and not result in the self.task object being deallocated in Release.

NSURLSessionDataTask *task = [session dataTaskWithRequest:req];
[task resume];
self.task = task;

P.S. Not sure why I can't link issues to this PR.

[retyui]

Hi
This module is unmentionable ⚠️! please use fork: https://github.com/RonRadtke/react-native-blob-util