Update rustls requirement from 0.18 to 0.19 (#246)

Updates the requirements on [rustls](https://github.com/ctz/rustls) to permit the latest version.
- [Release notes](https://github.com/ctz/rustls/releases)
- [Changelog](https://github.com/ctz/rustls/blob/main/OLDCHANGES.md)
- [Commits](https://github.com/ctz/rustls/compare/v/0.18.0...v/0.19.0)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Cargo.toml

@@ -31,7 +31,7 @@ once_cell = "1"
 qstring = "0.7"
 url = "2"
 socks = { version = "0.3.2", optional = true }
-rustls = { version = "0.18", optional = true, features = [] }
+rustls = { version = "0.19", optional = true, features = [] }
 webpki = { version = "0.21", optional = true }
 webpki-roots = { version = "0.20", optional = true }
 rustls-native-certs = { version = "0.4", optional = true }