Update Prometheus Go Module Dependency

[ihcsim]

promdump depends on a very old version (v1.8.2-0.20201015110737-0a7fdd3b7696) of Prometheus Go module. We should update go.mod to use a newer version. More info can be found in this issue. My recent attempt to upgrade this shows that there are some conflicts in the version of the go-openapi depended by kustomize (which is an indirect dependency of cli-runtime), and that depended by Prometheus.

[i4o]

Seems like v1.8.2 of prometheus go module was retracted. Are there any plans to fix this? As you probably know, there are more vulnerabilities at the moment, what are your plans with this project? Seems to be abandoned :).

[ihcsim]

I haven't been following the upstream go mod issue for a while. Ultimately, promdump only needs the github.com/prometheus/prometheus/tsdb[/*] packages. There is a drawn-out conversation in prometheus/prometheus#8852. Do you know if it's easier to use go mod to manage prometheus as a library these days?