Bump golangci-lint to v1.18.0 (#6004)
Bump golangci-lint to v1.18.0 (#6004)

It is required to support Go 1.13 (see
https://github.com/golangci/golangci-lint/issues/652).

Signed-off-by: Simon Pasquier <38e2d22e48be18381a59028f88390cad04670376@redhat.com>
keegancsmith/prometheus,keegancsmith/prometheus,keegancsmith/prometheus,alileza/prometheus,GoogleCloudPlatform/prometheus,prometheus/prometheus,keegancsmith/prometheus,GoogleCloudPlatform/prometheus,prometheus/prometheus,kangwoo/prometheus,Gouthamve/prometheus,kangwoo/prometheus,alileza/prometheus,keegancsmith/prometheus,Gouthamve/prometheus,GoogleCloudPlatform/prometheus,kangwoo/prometheus,prometheus/prometheus,Gouthamve/prometheus,prometheus/prometheus,alileza/prometheus,alileza/prometheus,kangwoo/prometheus,prometheus/prometheus,Gouthamve/prometheus,GoogleCloudPlatform/prometheus,GoogleCloudPlatform/prometheus,alileza/prometheus