fix(ci): pin dtolnay/rust-toolchain to commit SHA (SonarCloud hotspot)

Author: nikolay-e

.github/workflows/ci.yml

@@ -85,7 +85,7 @@ jobs:
       - uses: actions/checkout@v6
 
       - name: Install Rust
-        uses: dtolnay/rust-toolchain@stable
+        uses: dtolnay/rust-toolchain@3c5f7ea28cd621ae0bf5283f0e981fb97b8a7af9 # stable
 
       - name: Cache Cargo
         uses: actions/cache@v5