Fix subscription id mismtach

[Exca-DK]

Closes #230

[SC4RECOIN]

this did not fix linked issue for me
I still get cannot find websocket message handler for a new stream.... this should not happen with this change

in my opinion, this should just be a string so no assumptions are made about the size of the int
https://www.jsonrpc.org/specification states:
An identifier established by the Client that MUST contain a String, Number, or NULL value if included

or maybe use an even smaller id

// find available id
var id uint64 = 1
for ; ; id++ {
	if _, ok := c.subscriptionByRequestID[id]; !ok {
		break
	}
}

[Exca-DK]

Hi @SC4RECOIN,

Could you please confirm if it works now? During our tests, Uint32 passed successfully. We have updated it to a string as suggested and it should still work as intended.