Features from optional dependencies

ethers implicit feature

Enables ethers

ethers:

A complete Ethereum and Celo Rust library

Affects siwe::VerificationOpts.rpc_provider

serde implicit feature

Enables serde

serde:

A generic serialization/deserialization framework

typed-builder implicit feature

Enables typed-builder ^0.14.0

typed-builder:

Compile-time type-checked builder derive