Update `actions-rs/toolchain` action in workflows

The actions-rs/toolchain@v1 action is deprecated and unmaintained. Consider using dtolnay/rust-toolchain@stable or actions/setup-rust instead.
```suggestion
uses: dtolnay/rust-toolchain@stable
with:
toolchain: stable
targets: wasm32-unknown-unknown
components: rust-src
```

_Originally posted by @Copilot in https://github.com/0xMiden/miden-client/pull/1403#discussion_r2440084265_

Look for GitHub Actions workflow files (likely in .github/workflows/) that use 'actions-rs/toolchain@v1'. Replace the usage with the suggested dtolnay/rust-toolchain@stable configuration, ensuring the toolchain, targets, and components are set correctly. Verify the change by checking if the workflows still run successfully for Rust and WASM builds.

Rédigé par le modèle d'indexation à partir du texte de l'issue.