Windows failure due to prometheus/client_golang

[stefantalpalaru]

Failure during go get ./... in HEAD, on AppVeyor - https://ci.appveyor.com/project/nimbus/nim-libp2p/builds/27746839/job/dnpugbq12b2t298q#L579 :

# github.com/prometheus/client_golang/prometheus
..\goblin\pkg\mod\github.com\prometheus\[email protected]\prometheus\process_collector_windows.go:78:9: assignment mismatch: 2 variables but "golang.org/x/sys/windows".GetCurrentProcess returns 1 values

Upstream issue: prometheus/client_golang#642

[godcong]

it looks like a newer golang.org/x/sys version replaced the old tag version
replace
github.com/prometheus/client_golang v1.1.0
to
github.com/prometheus/client_golang v1.2.1

then retry it.