Add Liberty Testnet (chainId 13373)

[kaizennakamoto]

Adds Liberty Testnet to the chain registry.

• chainId: 13373
• Native currency: Liberty (LBRTY), 18 decimals
• RPC: https://testnet-rpc.libertychain.org (POST eth_chainId returns 0x343d)
• Explorer: Blockscout (EIP3091) at https://explorer.libertychain.org
• Icon: 512x512 PNG pinned on IPFS

RPC verified reachable and returning the correct chainId. JSON validated.

[github-actions]

You successfully submitted a PR! Due to the amount of PRs coming in: we will only look at PRs that the CI is happy with. We can also not hold your hand getting the CI green - just look how others that where merged did it and RTFM. So as long as there is any CI check that reports an error - no human will look at this. You might be able to ask for some support after supporting the project - e.g. by sending funds to lists.eth. When you fixed things after a requested change - then you also need to (re-)request a review.