Pin release artifacts Rust toolchain (#5669)

This fixes the build issue identified in #5664 at the toolchain level
rather than working around it in our own build. The next step in fixing
this will be to remove the nightly override in the future when the
toolchain becomes stable.

.github/workflows/build.yml

@@ -56,6 +56,12 @@ jobs:
       with:
         submodules: true
     - uses: ./.github/actions/install-rust
+      # Note that the usage of this nightly toolchain is temporary until it
+      # rides to stable. After this nightly version becomes stable (Rust 1.69.0)
+      # then this should switch back to using stable by deleting the `with` and
+      # `toolchain` options.
+      with:
+        toolchain: nightly-2023-01-31
     # On one builder produce the source tarball since there's no need to produce
     # it everywhere
     - run: ./ci/build-src-tarball.sh