Remove `Deref` implementation from non-pointer types

[alcuadrado]

I stumbled upon a Deref implementation in PendingTransaction, and I was told that they should only be used with pointer types. I didn't remove it to avoid generating conflicts, and instead, I'm just opening the issue with a list of the types implementing Deref.

Documentation explaining why Deref and DerefMut should only used for smart pointer.

Definition of Done Remove occurrences of Deref and DerefMut, wherever possible. A (non-exhaustive) list:

• [ ] ZeroXPrefixedBytes
• [ ] ReceiptLog
• [ ] FullBlockLo
• [ ] TestRpcClient
• [ ] BlockReceipt
• [ ] PendingTransaction
• [ ] MemPool
• [ ] FilterLog
• [ ] State
• [ ] Receipt
• [ ] Blockchain
• [ ] Block
• [ ] EdrContext
• [ ] Config
• [ ] PendingTransaction
• [ ] AccountModifierFn
• [ ] TestForkState
• [ ] TestForkState
• [ ] MineBlockResult