Unable to download files when Content-Encoding is chunked

[eagletmt]

MiniPortile#download_file_http relies on the Content-Length header, but it isn't sent when Content-Encoding is chunked. In this case, content_length_proc is called with nil.
https://github.com/flavorjones/mini_portile/blob/v2.3.0/lib/mini_portile2/mini_portile.rb#L454-L460
Although mini_portile requests with Accept-Encoding: identity, some servers (e.g., GitHub) respond with Content-Encoding: chunked

[flavorjones]

Closing the loop: this was addressed via #86 in v2.4.0.