Update caddy to v0.7.4.
Update caddy to v0.7.4.

Experimentally, this binary was built locally rather than coming from
the caddyserver.com/downloads build server.

sha256 f0d2939dbe7bf320430dcb15474f0a42316e77e511da28a39b484aa5ec3175d2 rootfs/bin/caddy

joshix/caddybox