gmg137 snap7-rs client.rs as_ct_write heap-based overflow

A vulnerability has been found in gmg137 snap7-rs up to 1.142.1. Affected is the function snap7_rs::client::S7Client::as_ct_write of the file /tests/snap7-rs/src/client.rs. The manipulation leads to heap-based buffer overflow. The attack can be initiated remotely. The exploit has been disclosed to the public and may be used.