chore(cargo): bump mail-builder from 0.4.2 to 0.4.3

Bumps [mail-builder](https://github.com/stalwartlabs/mail-builder) from 0.4.2 to 0.4.3.
- [Release notes](https://github.com/stalwartlabs/mail-builder/releases)
- [Changelog](https://github.com/stalwartlabs/mail-builder/blob/main/CHANGELOG.md)
- [Commits](https://github.com/stalwartlabs/mail-builder/commits)

---
updated-dependencies:
- dependency-name: mail-builder
  dependency-version: 0.4.3
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

Cargo.lock

@@ -66,7 +66,7 @@ iroh-gossip = { version = "0.35", default-features = false, features = ["net"] }
 iroh = { version = "0.35", default-features = false }
 kamadak-exif = "0.6.1"
 libc = { workspace = true }
-mail-builder = { version = "0.4.2", default-features = false }
+mail-builder = { version = "0.4.3", default-features = false }
 mailparse = { workspace = true }
 mime = "0.3.17"
 num_cpus = "1.17"