jsonrpc: return a warning everytime a json response get handled

[vincenzopalazzo]

          This gives me the warning everytime I run `lampo-cli --network regtest getinfo`. 

2024-05-24T16:13:35.386Z WARN jsonrpc event invalid: Event { key: Connect, source: Source { fd: 15, events: 519, revents: 32 } }. [lampo-jsonrpc/src/lib.rs:281]

This is the basic flow of events whenever I am querying the node.

1. RPCEvent::Accept
2. RPCEvent::Connect && event.is_readable()
3. RPCEvent::Connect and the event.is_invalid() -> This throws the warning.

Originally posted by @Harshit933 in #219 (comment)

[Harshit933]

I will take this.

[vincenzopalazzo]

I do not think this is a task for you @Harshit933, this is a problem on how we use pool at the kernel level

Or your already know how to fix it?

[Harshit933]

I do not know. But if you are working on this you would do far better than me :)

[vincenzopalazzo]

I think we should not waste time in bug that we do not know how to solve. You have already a lot of work on your plate

[vincenzopalazzo]

Fixed in #242