Bump mailparse from 0.14.1 to 0.15.0

Bumps [mailparse](https://github.com/staktrace/mailparse) from 0.14.1 to 0.15.0.
- [Commits](staktrace/mailparse@v0.14.1...v0.15.0)

---
updated-dependencies:
- dependency-name: mailparse
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Cargo.toml

@@ -30,7 +30,7 @@ audit           = { version = "0.7.3" }
 cargo-audit     = { version = "0.20.0" }
 charset         = { version = "0.1" }
 lambda_runtime  = { version = "0.11" }
-mailparse       = { version = "0.14" }
+mailparse       = { version = "0.15" }
 rusoto_core     = { version = "0.48" }
 rusoto_ses      = { version = "0.48" }
 serde           = { version = "1", features = ["derive"] }