Release Splice version 3.0.0-alpha.45.
Release Splice version 3.0.0-alpha.45.

 * Add Fracture dependency.
 * Upgrade `riffle` to `2.0.0-alpha.61`.
 * Upgrade `b-tree` to `2.0.0-alpha.85`.

Closes #214.

bigeasy/splice,bigeasy/splice