v0.5.2

A dependency-refresh release. No bsrs code, API, or behaviour changes.

Changed

• Based the EPICS CA/PVA backends on epics-rs 0.29.3 (from 0.29.2). The
  release makes a record's monitor state advance on every value-class post
  whether or not the field has a subscriber, so a move that finished with no
  .DMOV monitor no longer swallows the next subscriber's 1→0 transition,
  which is the done-PV wait every ca_motor put relies on. No bsrs source
  change was needed.
• Cargo.lock moves chacha20, der and spin off their yanked versions
  (0.10.1, 0.8.0, 0.9.8) to the compatible successors; none is a direct
  dependency and no advisory names the old versions.