chore(deps): update to sqlx 0.8

[ellie]

This included some breaking changes, see: https://github.com/launchbadge/sqlx/pull/2973

Luckily not too much effort to fix :)

Checks

• [ ] I am happy for maintainers to push small adjustments to this PR, to speed up the review cycle
• [ ] I have checked that there are no existing pull requests for the same thing