In `rust-bitcoin` the `blockdata` module is a code organisation thing,
it should never have been public. One day those guys would like to
remove it, so as not to be a PITA for `bdk` when they do lets remove all
usage of `blockdata::` now.
Internal change only, no externally visible changes.
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".
