needs update to build on recent golang

[Paalon]

Golang have changed how to use module (I'm not familiar with golang) so it needs update. Currently it fails to make:

$ make
go get github.com/jessevdk/go-assets-builder
go: go.mod file not found in current directory or any parent directory.
	'go get' is no longer supported outside a module.
	To build and install a command, use 'go install' with a version,
	like 'go install example.com/cmd@latest'
	For more information, see https://golang.org/doc/go-get-install-deprecation
	or run 'go help get' or 'go help install'.
make: *** [get-build-deps] Error 1