fix(deps): update rust crate async-ssh2-tokio to v0.8.15 (#34)

| datasource | package          | from   | to     |
| ---------- | ---------------- | ------ | ------ |
| crate      | async-ssh2-tokio | 0.8.12 | 0.8.15 |

Co-authored-by: dreadnode-renovate-bot[bot] <184170622+dreadnode-renovate-bot[bot]@users.noreply.github.com>

Author: dreadnode-renovate-bot[bot]