fix: rustls allow usage or system root certificates

Expose a feature of the reqwest crate that allows to use the system
certificates.

Signed-off-by: Flavio Castelli <fcastelli@suse.com>

Cargo.toml

@@ -29,6 +29,7 @@ maintenance = {status = "actively-developed"}
 default = ["native-tls", "test-registry"]
 native-tls = ["reqwest/native-tls"]
 rustls-tls = ["reqwest/rustls-tls"]
+rustls-tls-native-roots = ["reqwest/rustls-tls-native-roots"]
 trust-dns = ["reqwest/trust-dns"]
 # This features is used by tests that use docker to create a registry
 test-registry = []