Infura subscription not working anymore

Currently, subscriptions to Infura cause the following error:

```
json: cannot unmarshal string into Go value of type types.txJSON
```

The error is logged here: https://github.com/flashbots/mempool-dumpster/blob/7dd7061fc3f2a4128abe7fd0d1d88d56186be9e5/collector/node_conn.go#L75

It stems from the [go-ethereum gethclient](https://github.com/ethereum/go-ethereum/blob/f1794ba2788baf34489847bfa9ca00e067507db0/ethclient/gethclient/gethclient.go) subscription code that's suddenly unable to parse the result from Infura subscriptions into [txJSON](https://github.com/ethereum/go-ethereum/blob/f1794ba2788baf34489847bfa9ca00e067507db0/core/types/transaction_marshalling.go#L30).