The PR enables
[`nolintlint`](https://golangci-lint.run/usage/linters/#nolintlint)
linter and fixes up appeared issues.
Changes:
- Enable `nolintlint` in `.golangci.yml` config.
- Remove unused `//nolint:` comments.
- Fix `nolint` comment format by removing spaces (`// nolint: dupl` ->
`//nolint:dupl`)
Co-authored-by: Carlos Alexandro Becker <caarlos0@users.noreply.github.com>