Not compiling

Hi,

I get 2 compile errors. Guess, the dependencies have changed?

```
pkg/mod/github.com/itskoko/prometheus-renderer@v0.0.5/renderer.go:37:12: assignment mismatch: 2 variables but plot.New returns 1 values
pkg/mod/github.com/itskoko/prometheus-renderer@v0.0.5/renderer.go:65:12: assignment mismatch: 2 variables but r.API.QueryRange returns 3 values
```