fix: treat connection resets as connection closed by peer

[iloveitaly]

This was the original error message I received:

Embassy/Transport.swift:203: Fatal error: Failed to send, errno=54, message=Connection reset by peer

[iloveitaly]

@fangpenlin thoughts on this?

[mikebuss]

I've also had this issue, but my fix involved changing handleRead to return if the read failed. For my use case, this solves the "Connection reset by peer" issue above.

private func handleRead() {
        // ensure we are not closed
        guard !closed else {
            return
        }
        guard reading else {
            return
        }
        var data: Data!
        do {
            data = try socket.recv(size: Transport.recvChunkSize)
        } catch {
            return
        }
        guard data.count > 0 else {
            closedByPeer()
            return
        }
        // ensure we are not closing
        guard !closing else {
            return
        }
        if let callback = readDataCallback {
            callback(data)
        }
    }