fix: package name and other moved repos

[Tazer]

When trying to go get github.com/hashicorp/go-metrics

This should fix it so it's possible to do above and not get:

go: downloading github.com/hashicorp/go-metrics v0.4.1
go: github.com/hashicorp/go-metrics@v0.4.1: parsing go.mod:
        module declares its path as: github.com/armon/go-metrics
                but was required as: github.com/hashicorp/go-metrics

[hashicorp-cla]

All committers have signed the CLA.

[analogue]

Thanks!

[remmelt]

Can you please create a tag for this release?