Trantorian1

# Pull Request type - Bugfix ## What is the current behavior? [`LegacyContractClass`](https://github.com/xJonathanLEI/starknet-rs/blob/400deb6f058447e8b67316a92ecd9ad3b6d4330c/starknet-core/src/types/contract/legacy.rs#L31) deserialization fails on classes with a missing ABI. Earliest example of this is class [`0x01cbbbd9543d07a5769e0d17bca0ede054082a27689aa7b6b3731851e0c65326`](https://starkscan.co/class/0x0371b5f7c5517d84205365a87f02dcef230efa7b4dd91a9e4ba7e04c5b69d69b#overview) at block...

### Is there an existing issue? - [X] I have searched the existing issues ### Motivation `Felt` is not zeroized on drop which might leak sensitive information into RAM, notably...