Only POAP NFTs supported on Gnosis

As announced at the beginning of the month, we have sunset support for NFTs on Gnosis (xDAI) except for the popular POAP contract (0x22c1f6050e56d2876009903609a2cc3fef83b415).

We're making this change because other contracts on Gnosis chain suffer from a high volume of spam. This will allow us to focus resources on the contract (POAP) that is by far the most interacted with and used by our customers.