chore: Upgrade rusqlite dependency from 0.32 to 0.40.1

[kkuehl]

Summary

Upgrades rusqlite from 0.32 to 0.40.1, bringing 8 minor versions of improvements including bug fixes, performance enhancements, and updated SQLite bundled version.

Changes

1. rusqlite: 0.32 → 0.40.1
2. tokio-rusqlite: Now uses fork kkuehl/tokio-rusqlite with rusqlite 0.40.1 support

tokio-rusqlite Fork Rationale

The tokio-rusqlite crate is a dependency of rig-sqlite. Unfortunately, the upstream maintainer has not merged rusqlite upgrade PRs:

• PR #52 (upgrade to 0.39) has been open since March 2026 with no maintainer response
• Multiple community members have requested the merge in comments

Until upstream merges a rusqlite 0.40+ compatible version, this PR uses a fork with the necessary 2-line change to unblock rig users who need modern rusqlite features.

Alternative Approach

If using a git dependency for tokio-rusqlite is not acceptable, consider:

1. Waiting for upstream to merge rusqlite upgrades
2. Switching to an alternative async SQLite wrapper
3. Maintaining the fork as rig-tokio-rusqlite

Testing

• All existing tests pass
• rig-sqlite builds successfully with the changes