fix: include alloy-contract?/pubsub in pubsub feature

[StackOverflowExcept1on]

Motivation

This fixes the compilation of the following code:

let my_event_filter = contract.MyEvent_filter().subscribe().await?;

alloy = { git = "https://github.com/alloy-rs/alloy", branch = "main", features = ["contract", "pubsub"] }

[DaniPopes]

Thanks!