Typo in NethereumMetamask.jslib

[fukaraadam]

I think there is a little typo in NethereumMetamask.jslib which causes to empty public key when accounts changed.
`

    ethereum.on("accountsChanged",
            function (accounts) {
                //console.log(accounts[0]);
                let account = "";
                if(account[0] !== undefined){
                    account = account[0];
                }
                nethereumUnityInstance.SendMessage(parsedObjectName, parsedCallbackAccountChange, account);
            });
    ethereum.on("chainChanged",
            function (chainId) {
                // console.log(chainId);
                nethereumUnityInstance.SendMessage(parsedObjectName, parsedCallbackChainChange, chainId.toString());
            });

`

in ethereum.on("accountsChanged, ...) accounts array typed as "account" (without 's')