Use latest stable rust for valgrind/fmt jobs

Author: ctz

.github/workflows/libssl.yaml

@@ -48,6 +48,8 @@ jobs:
       - uses: actions/checkout@v4
         with:
           persist-credentials: false
+      - name: Install rust toolchain
+        uses: dtolnay/rust-toolchain@stable
       - name: Install valgrind
         run: sudo apt-get update && sudo apt-get install -y valgrind
       - name: Install build dependencies
@@ -84,9 +86,8 @@ jobs:
         with:
           persist-credentials: false
       - name: Install rust toolchain
-        uses: dtolnay/rust-toolchain@master
+        uses: dtolnay/rust-toolchain@stable
         with:
-          toolchain: 1.67.1
           components: rustfmt
       - name: Check Rust formatting
         run: cargo fmt --all -- --check