ci: bump dtolnay/rust-toolchain

Bumps [dtolnay/rust-toolchain](https://github.com/dtolnay/rust-toolchain) from b3b07ba8b418998c39fb20f53e8b695cdcc8de1b to 67ef31d5b988238dd797d409d6f9574278e20537.
- [Release notes](https://github.com/dtolnay/rust-toolchain/releases)
- [Commits](dtolnay/rust-toolchain@b3b07ba...67ef31d)

---
updated-dependencies:
- dependency-name: dtolnay/rust-toolchain
  dependency-version: 67ef31d5b988238dd797d409d6f9574278e20537
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/test.yml

@@ -80,7 +80,7 @@ jobs:
 
       - name: Install Rust
         if: matrix.arch != 'x86'
-        uses: dtolnay/rust-toolchain@b3b07ba8b418998c39fb20f53e8b695cdcc8de1b # v1
+        uses: dtolnay/rust-toolchain@67ef31d5b988238dd797d409d6f9574278e20537 # v1
         with:
           toolchain: stable