Fixing a conflict (probably due to unrecord)

Dependencies

• [2] X7OHUPL5 Fixing a bug in unrecord, and fixing the tests
• [3] X243Z3Y5 Recording only the required metadata (can even be changed later!)
• [4] SXEYMYF7 Fixing the bad changes in history (unfortunately, by rebooting).
• [5] VO5OQW4W Removing anyhow in libpijul

Change contents

• edit in libpijul/src/record.rs at line 11
  [3.489225]→[3.489225:489267](∅→∅)
  − use std::collections::{HashMap, HashSet};
• edit in libpijul/src/change.rs at line 3
  [3.831311]→[2.1173:1226](∅→∅)
  − use crate::pristine::*;

  − use chrono::{DateTime, Utc};