Should change the token URI when mint_nft function called

[y0unghe]

It seems this mutate_token_properties function won't set the correct token URI when a new token was minted. Each token should have different Metadata URI like https://arweave.net/bLlRFRTUioMMbT7eIqxehNvfrjwtK_Dujk6PIA0HU_4/1.json for token 1 and https://arweave.net/bLlRFRTUioMMbT7eIqxehNvfrjwtK_Dujk6PIA0HU_4/2.json for token 2.

It would be great to have this function.