chore(deps): Bump thiserror from 2.0.17 to 2.0.18 (#3)

Bumps [thiserror](https://github.com/dtolnay/thiserror) from 2.0.17 to 2.0.18.
- [Release notes](https://github.com/dtolnay/thiserror/releases)
- [Commits](https://github.com/dtolnay/thiserror/compare/2.0.17...2.0.18)

---
updated-dependencies:
- dependency-name: thiserror
  dependency-version: 2.0.18
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

filtermail/Cargo.toml

@@ -14,7 +14,7 @@ base64 = "0.22.1"
 serde = { version = "1.0.228", features = ["derive"] }
 serini = "0.2.2"
 tokio = { version = "1.49.0", features = ["full"] }
-thiserror = "2.0.17"
+thiserror = "2.0.18"
 mailparse = "0.16.1"
 lettre = { version = "0.11.19", default-features = false, features = [
   "smtp-transport",