API endpoint /api/account/addresstokenbalance is returning ERC721s

[itsacoyote]

🐛 Bug Report

Getting the token balance of ERC20s for an address returns a list that includes ERC721s.

📝 Description

The balanceService.getBalances(address) is returning a list of ERC20s along with ERC721s

🔄 Reproduction Steps

https://block-explorer-api.mainnet.zksync.io/api?module=account&action=addresstokenbalance&address=0x0f6bfc4C284e489B404715B3F2610b0eb50FdE35

as well as:

https://block-explorer-api.mainnet.zksync.io/address/0x0f6bfc4C284e489B404715B3F2610b0eb50FdE35

Checking the return data, the last item in the list is "empty" data for a token with a quantity of 1.

{
      // Contract address is for CyfrinFoundryCourseNft 
      "TokenAddress": "0xBbA202c6DA89646F13C11a63C4aF182E4fFd4c2e",
      "TokenName": "",
      "TokenSymbol": "",
      "TokenQuantity": "1",
      "TokenDivisor": ""
  }

🤔 Expected Behavior

Only ERC20s listed for an address.

😯 Current Behavior

ERC20 and ERC721 are listed

[itsacoyote]

This could be resolved with the work in this PR? #384