chore: sepolia deployment testing multisig upgrade

[AuHau]

This is just to showcase the upgrade of the Marketplace contract using a multisig wallet.

I have deployed Safe Multisig Wallet and Marketplace to Sepolia with having the ProxyAdmin assigned to the Safe Multisig and then performed the upgrade.

• Here is the Marketplace's Proxy: https://sepolia.etherscan.io/address/0x904cd89A4783DcDaa4577e5812645aEDf3653cC8
• Here is the initial version of Marketplace's implementation: https://sepolia.etherscan.io/address/0x61cb8e9b84b6efd0e15ecedb66fb5d337865c0ad
• Here is the upgraded implementation version: https://sepolia.etherscan.io/address/0x1f40f019d4e82dd2c40cfcfc4eada1d01ebc4288

(The difference between the implementations can be seen in the added newShinyMethod() method)

Etherscan nicely shows the upgrades:

The upgrade process is like:

1. Deploy a new version of the Marketplace's implementation
2. In Safe Wallet you need to "New transaction -> Transaction Builder", where you need to pass in the ProxyAdmin ABI, which then allows easy construction of the upgradeAndCall() call, which switches the implementation in the Proxy contract.

If the process will need to be streamlined, then there is a possibility to create a JS/bash script that would propose the upgrading transaction using Safe Transaction Service API:

• https://docs.safe.global/sdk/api-kit/guides/propose-and-confirm-transactions
• https://docs.safe.global/core-api/transaction-service-reference/sepolia#Create-Multisig-Transaction