CURLOPT_HTTP_VERSION(3) on macOS

The text 64219ffd64c0, as macOS 10.12.5, macOS 10.12.4, macOS 10.12.3, macOS 10.12.2, macOS 10.12.1, macOS 10.12 shipped it.

specify HTTP protocol version to use

CURLOPT_HTTP_VERSION(3) on macOS now