ci: Bump dtolnay/rust-toolchain (#8)

Bumps [dtolnay/rust-toolchain](https://github.com/dtolnay/rust-toolchain) from efa25f7f19611383d5b0ccf2d1c8914531636bf9 to 3c5f7ea28cd621ae0bf5283f0e981fb97b8a7af9.
- [Release notes](https://github.com/dtolnay/rust-toolchain/releases)
- [Commits](dtolnay/rust-toolchain@efa25f7...3c5f7ea)

---
updated-dependencies:
- dependency-name: dtolnay/rust-toolchain
  dependency-version: 3c5f7ea28cd621ae0bf5283f0e981fb97b8a7af9
  dependency-type: direct:production
...

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Author: dependabot[bot]

.github/workflows/mirror.yml

@@ -127,7 +127,7 @@ jobs:
           fetch-depth: 0
 
       - name: Setup Rust
-        uses: dtolnay/rust-toolchain@efa25f7f19611383d5b0ccf2d1c8914531636bf9 # stable
+        uses: dtolnay/rust-toolchain@3c5f7ea28cd621ae0bf5283f0e981fb97b8a7af9 # stable
         with:
           toolchain: stable