net-mgmt/unbound_exporter: Update to 0.4.1

• Update to 0.4.1
• Update repo location
• Simplify Makefile by using GO_MODULE rather than GH_TUPLE
• Add missing SUB_LIST to Makefile
• Re-factor init script

Changes: https://github.com/letsencrypt/unbound_exporter/releases/tag/v0.4.1

PR: 267609
PR: 265255
Approved by: aduitsis@cpan.org (maintainer timeout, > 1 month)