v0.51.1

- AppExpiry and DeviceDeregistered errors are now properly reported on
  connect; previously the types were exposed but would never be
  created in practice. If this sounds like a duplicate release note,
  well, the v0.51.0 implementation wasn't quite right!

- Node: The node module file is now named
  @signalapp+libsignal-client.node instead of node.napi.node.
  The directory structure for prebuilds remains the same.

- Updated rustc, cargo-about, curve25519-dalek