Upgrade:
- bitcoin to v0.31.0
- miniscript to v11.0.0
Note: The bitcoin upgrade includes improvements to the
`Transaction::weight()` function, it appears those guys did good, we
no longer need to add the 2 additional weight units "just in case".
and `into_confirmation_time_tx_graph`, since now it makes
sense to use `TxGraph::update_last_seen_unconfirmed`.
Also, use `update_last_seen_unconfirmed` in examples for
electrum/esplora. We show how to update the last seen
time for transactions by calling `update_last_seen_unconfirmed`
on the graph update returned from a blockchain source, passing
in the current time, before applying it to another `TxGraph`.
