promplot - assistance with golang port

Hi,

I looking for a tool which can easily generate a screenshot from
Prometheus metrics and I found https://github.com/qvl/promplot

I have work in progress port, but it fails to build with:

...
go install -modcacherw -v -p 1 github.com/qvl/promplot ; fi;
cannot find module providing package github.com/qvl/promplot: working directory is not part of a module
*** Error 1 in . (/home/mkucharski/openbsd/ports/lang/go/go.port.mk:153 'do-build')

Any idea what I'm doing wrong?

--
Regards,
Mikolaj