build: replace actions-rs/toolchain with dtolnay/rust-toolchain

actions-rs/toolchain is unmaintained, hence replace it with
dtolnay/rust-toolchain

See: #5929

Signed-off-by: Ruslan Mstoi <ruslan.mstoi@intel.com>

.github/workflows/build.yaml

@@ -29,11 +29,10 @@ jobs:
         run: sudo apt install -y musl-tools
 
       - name: Install Rust toolchain (${{ matrix.rust }})
-        uses: actions-rs/toolchain@v1
+        uses: dtolnay/rust-toolchain@stable
         with:
           toolchain: ${{ matrix.rust }}
           target: ${{ matrix.target }}
-          override: true
 
       - name: Build (default features)
         run: cargo rustc --locked --bin cloud-hypervisor -- -D warnings -D clippy::undocumented_unsafe_blocks

.github/workflows/fuzz-build.yaml

@@ -20,11 +20,10 @@ jobs:
       - name: Code checkout
         uses: actions/checkout@v4
       - name: Install Rust toolchain (${{ matrix.rust }})
-        uses: actions-rs/toolchain@v1
+        uses: dtolnay/rust-toolchain@stable
         with:
             toolchain: ${{ matrix.rust }}
             target: ${{ matrix.target }}
-            override: true
       - name: Install Cargo fuzz
         run: cargo install cargo-fuzz
       - name: Fuzz Build