Deprecated SecureTransport dependency

[qzix]

Telegraph uses CocoaAsyncSocket that internally uses SecureTransport framework (for TLS support) that is deprecated since iOS 13 in favour of Network framework. Apple may accidentally drop SecureTransport framework from iOS so Telegraph will stop working as well.

Telegraph appears to be well-written and modular, Network framework shares similar concepts with CocoaAsyncSocket. Therefore, it should be feasible for Telegraph to transition from CocoaAsyncSocket and become future-proof.

[yvbeek]

At some point I'll have to make the switch to Network framework. I'm not to sure how much work that's going to be 😅