Try to fix iron

Signed-off-by: Yadunund <[email protected]>

.github/workflows/build.yaml

@@ -21,7 +21,7 @@ jobs:
       run: |
         apt update && apt install -y curl
     - name: Setup Rust
-      uses: dtolnay/rust-toolchain@stable
+      uses: dtolnay/rust-toolchain@1.75.0
     - uses: actions/checkout@v2
     - name: rosdep
       run: |