Supporting Amoy Testnet now that Mumbai is deprecated

[gittygoo]

✅ Prerequisites

• [x] Did you perform a cursory search of open issues? Is this feature already requested elsewhere?
• [x] Are you reporting to the correct repository (magic-sdk)?

✨ Feature Request

Polygon Mumbai is deprecated, add support for amoy

🧩 Context

https://magic.link/docs/blockchains/featured-chains/polygon seems to only support mumbai which is deprecated, we're trying to use it with amoy alongside web3modal https://github.com/WalletConnect/web3modal/issues/2284

💻 Examples

[Do you have any example(s) for the requested feature? If so, describe/demonstrate your example(s) here.]