Update proto definitions to 0.18.1

[carbolymer]

The proto definitions are out of sync with utxorpc. Update them to version 0.18.1.

[github-actions]

This issue is stale because it has been open 90 days with no activity. Remove stale label or comment or this will be closed in 100 days.

[github-actions]

This issue is stale because it has been open 90 days with no activity. Remove stale label or comment or this will be closed in 100 days.