Add request timeout to Esplora client in example

[rishabhyadav03]

This PR adds a request timeout to the Esplora client used by the example application. Configuring a timeout helps avoid hanging network requests and makes the example more robust for real world usage.

[oleonardolima]

NACK 0a36b0a

As also mentioned in this other comment it does not belong to the README.md. Maybe the example could use the timeout, but that would require it to be reworked to actually be an argument/parameter, instead of just setting it up straight to 60, as it's currently being done in the PR.