Bump der-parser to 9.0 (#574)

This also removes syn 1.0 from the crate tree.

Author: adamchalmers

Cargo.lock

@@ -41,7 +41,7 @@ tokio = { version = "1.32.0", features = [
 async-trait = "0.1"
 x25519-dalek = { version = "2", features = ["static_secrets"] }
 x509-parser = "0.16"
-der-parser = "8.1"
+der-parser = "9.0"
 rcgen = "0.13"
 ring = "0.17"
 rustls = { version = "0.23", default-features = false, features = ["std", "ring"] }