Fix missing #![no_std]

Author: sosthene-nitrokey

types/src/lib.rs

@@ -1,6 +1,8 @@
 // Copyright (C) Nitrokey GmbH
 // SPDX-License-Identifier: Apache-2.0 or MIT
 
+#![no_std]
+
 use heapless_bytes::Bytes;
 use serde::{Deserialize, Serialize};
 use trussed_core::types::SerializedKey;