fix(*): bump golangci-lint; fix linting err

[vdice]

• bumps golangci-lint version to latest

  • this was motivated by seeing quite lengthy output in CI using the previous/outdated version, e.g. https://brigadecore.github.io/kashti/jobs/tests-01dvcyr1x6pk73cm2fh2v6h9xz. It appears the bump eliminates this issue; see the test run here: https://brigadecore.github.io/kashti/jobs/tests-01dvedzvxfvn6beeb8k1r8a245

• addresses the following linting error seen locally:

 $ make lint
golangci-lint run --config ./golangci.yml
driver/kubernetes/kubernetes.go:400:2: S1031: unnecessary nil check around range (gosimple)
    if mergeWith != nil {
    ^
make: *** [lint] Error 1

[carolynvs]

So say we all