CI: Install Rust on self-hosted runners

Author: mkroening

.github/workflows/ci.yml

@@ -65,6 +65,8 @@ jobs:
     - uses: actions/checkout@v3
       with:
          submodules: true
+    - name: Install Rust toolchain
+      uses: dtolnay/rust-toolchain@stable
     - name: Build dev profile
       run: cargo build -Zbuild-std=std,panic_abort --target x86_64-unknown-hermit --package rusty_demo
     - name: Install uhyve