Bump version to 4.13.0

• Diff: https://gitlab.com/gitlab-org/gitlab-qa/compare/v4.12.0...882133dac16c8adaaeac3e0fba8649133e8812b3

• Release notes:

### New scenarios and scenario updates

- !338 feat: add SMTP scenario.

### Fixes

- !335 Set LANG to C.UTF-8

### Other changes (CI, backstage)

- !337 Pass through the CI_RUNNER_ID env var

• Checklist before merging:

  • Diff link is up-to-date.
  • Based on the diff, lib/gitlab/qa/version.rb is updated, according to SemVer.
  • Release notes are accurate.

• Checklist after merging:

  • Create a tag for the new release version.