server: Upgrade validator to 0.16

0.17 contains multiple undocumented breaking changes, we can wait with
that upgrade.

Author: svix-jplatte

server/Cargo.lock

@@ -42,7 +42,7 @@ opentelemetry = "0.22.0"
 opentelemetry_sdk = { version = "0.22.1", features = ["rt-tokio"] }
 opentelemetry-http = "0.11.0"
 opentelemetry-otlp = { version = "0.15.0" }
-validator = { version = "0.14.0", features = ["derive"] }
+validator = { version = "0.16.0", features = ["derive"] }
 jwt-simple = "0.11.6"
 ed25519-compact = "2.1.1"
 chrono = { version="0.4.26", features = ["serde"] }