Add Ethereum ephemery

[riva-infinex]

Gm,

I'm new to web3 and would like to use ephemery as described here https://ethereum.org/developers/docs/networks/#ephemery

This makes it ideal for (...) 'hello world' kind of applications

= exactly my case.

Unfortunately I can't see this chain declared here nor in viem

It's not mentioned in any issue as well.

Is there a technical reason it's not listed here? Could it be added? Thanks!