Release 2.18.0.0

[rlueckl]

OpenSearch 2.18.0 has been released, see release notes. Official OpenSearch release ticket: https://github.com/opensearch-project/opensearch-build/issues/5004

Checklist:

• [ ] Compatibility Matrix is updated (TODO: link to PR)
• [ ] Release 2.18.0.0 tag is present in the repo
• [ ] Release artifacts are available and downloadable
• [ ] Release notes published
• [ ] Forum announcement published

[rlueckl]

Hi! OpenSearch 2.18.0 was released on 2024-10-28, so I thought I'd open a ticket for a new prometheus-exporter version as well. I hope that's okay.

[ektropy]

There is a PR for this, #316.