v0.5.1

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

Changed

• Based the EPICS CA/PVA backends on epics-rs 0.29.2 (from 0.29.1). The
  release moves the SNL program start gate into epics-base-rs
  (spawn_program awaits wait_for_pini at the one spawn site), which is
  what makes the mini-beamline kohzuCtl boot with the right d-spacing; no
  bsrs source change was needed.
• MSRV is now 1.94 (from a declared 1.80). The old floor had been
  unachievable since 0.24.3: epics-base-rs is edition 2024, so no toolchain
  below 1.85 can build the CA/PVA backends at all. 1.94.0 is the channel
  epics-rs pins for itself, and the workspace is verified to build and test
  on exactly that toolchain.

Fixed

• The 0.4.2 section's date: the tag and publish landed on 2026-09-04 (KST),
  a day after the date the changelog carried.