Bump version to 0.13.0

This contains:

• https://gitlab.com/gitlab-org/gitlab-triage/merge_requests/70
• https://gitlab.com/gitlab-org/gitlab-triage/merge_requests/72
• https://gitlab.com/gitlab-org/gitlab-triage/merge_requests/73
• https://gitlab.com/gitlab-org/gitlab-triage/merge_requests/74
• https://gitlab.com/gitlab-org/gitlab-triage/merge_requests/75