`install.sh` does not fetch the most recent `dub` version

[Alex-Muirhead]

When installing dub with ./install.sh install dub, it will default to v1.22.0, despite later versions being available.
It seems the script queries https://dlang.github.io/dub/LATEST which returns v1.22.0, but I'm not sure where best to report this.

installer/script/install.sh

Lines 749 to 754 in 50a59aa

	local mirrors=(
	"https://dlang.github.io/dub/LATEST"
	"https://code.dlang.org/download/LATEST"
	)
	logV "Determining latest dub version (${mirrors[0]})."
	DUB_VERSION="$(fetch "${mirrors[@]}" | sed 's/^v//')"