trying to update the rust in the github actions

Author: Richard B

.github/workflows/release-concordium-cis2.yaml

@@ -29,6 +29,16 @@ jobs:
         with:
           submodules: recursive
 
+      # -----------------------------------------------------------------
+      # NEW STEP: Set up the modern Rust toolchain
+      # Use a specific version (e.g., '1.70.0') or 'stable'
+      - name: Install Rust Toolchain
+        uses: actions-rs/toolchain@v1 # OR use dtolnay/rust-toolchain@stable
+        with:
+          toolchain: stable # Use the latest stable version
+          override: true
+      # -----------------------------------------------------------------
+
       # Validate that the tag version matches the version in Cargo.toml
       - name: validate tag version has correct matching tag
         run: |