feat: add sepolia network under ethereum ecosystem [APE-694]

[challet]

What I did

• add the sepolia network to ape_ethereum
• add the sepolia network to ape_geth

How I did it

By adding references to it where it seemed suitable

How to verify it

ape console --network etherum:sepolia:[rpc-url]
ape console --network etherum:sepolia:geth 

Haven't tried the second one, see the geth PR about sepolia support

Checklist

• All changes are completed
• New test cases have been added (more specifically : test data to an existing case)
• Documentation has been updated (the new network is shown in the ape networks list command output, if that fells under documentation)

[challet]

I tried to add it to the EthereumConfig class as well but that led to a validation error that I didn't get

pydantic.error_wrappers.ValidationError: 1 validation error for EthereumConfig
sepolia
field required (type=value_error.missing)

Edit : I think I understand it is for plugins to have the property implemented