Migrating from Gun 1.1 to 1.2

Gun 1.2 adds support for the CONNECT request over HTTP/1.1 connections.

Features added

• CONNECT requests can now be issued on HTTP/1.1 connections. The tunneled connection can use any of the protocols Gun supports: HTTP/1.1, HTTP/2 and Websocket over both TCP and TLS transports. Note that Gun currently does not support tunneling a TLS connection over a TLS connection due to limitations in Erlang/OTP.
• Gun supports sending multiple CONNECT requests, allowing the tunnel to the origin server to go through multiple proxies.
• Gun supports sending CONNECT requests with authorization credentials using the Basic authentication mechanism.
• Update Cowlib to 2.6.0

Functions added

• The functions gun:connect/2,3,4 have been added. They can be used to initiate CONNECT requests on HTTP/1.1 connections.