feat(add): Add Nexus Mainnet - Safe Contract v1.3.0

[alfredolopez80]

Summary

• Add Nexus Mainnet chain ID 3946 as canonical for Safe Contract v1.3.0 assets

Add new chain

Template to provide information about the new chain. Only add extra information in the bottom section. Ensure that the contracts are deployed on the chain, if not deploy with safe-contracts. Only one chain ID, one Safe version and one deployment type per PR. The RPC will be taken from DefiLlama's ChainList. This entire paragraph should be deleted.

Please fill the following form:

Provide the Chain ID (Only 1 chain id per PR).

• Chain_ID: 3946

Relevant information:
https://explorer.nexus.xyz/

Validation

• npm run lint:fix

[agusgonzaleznic]

Overriding commit signature requirement as this is a new rule that will be added to a contributors.md file for communication.
PR code was reviewed.