cargo: bump native-tls from 0.2.7 to 0.2.8 (#2597)

Bumps [native-tls](https://github.com/sfackler/rust-native-tls) from 0.2.7 to 0.2.8.
- [Release notes](https://github.com/sfackler/rust-native-tls/releases)
- [Changelog](https://github.com/sfackler/rust-native-tls/blob/master/CHANGELOG.md)
- [Commits](https://github.com/sfackler/rust-native-tls/compare/v0.2.7...v0.2.8)

---
updated-dependencies:
- dependency-name: native-tls
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Cargo.toml

@@ -42,7 +42,7 @@ lettre_email = { git = "https://github.com/deltachat/lettre", branch = "master"
 libc = "0.2.101"
 log = {version = "0.4.8", optional = true }
 mailparse = "0.13.5"
-native-tls = "0.2.3"
+native-tls = "0.2.8"
 num_cpus = "1.13.0"
 num-derive = "0.3.0"
 num-traits = "0.2.6"