Fix rust-toolchain action name in CI

Author: ekg

.github/workflows/ci.yml

@@ -16,7 +16,7 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: Install Rust toolchain
-        uses: dtolnay/rust-action@stable
+        uses: dtolnay/rust-toolchain@stable
 
       - name: Cache cargo registry
         uses: actions/cache@v4