[torii] Panic when updating cursor

[edisontim]

In a scenario where we're subscribed to event_messages updates and to the torii relay (the issue doesn't occur when not subscribed to ws, I believe), the QueryType::UpdateCursors crashes on this line

dojo/crates/torii/core/src/executor.rs

Line 337 in c364d13

num_transactions / (now.elapsed().as_secs() - cursor_timestamp)

in this scenario I believe we need to calculate the difference between now and the cursor's timestamp but the current code subtracts the time difference between the moment we created the now and the cursor's timestamp