Fix CI toolchain version

Author: chris ha

.github/workflows/rust.yml

@@ -16,6 +16,8 @@ jobs:
 
     steps:
     - uses: actions/checkout@v3
+    - name: Install stable Rust toolchain
+      uses: dtolnay/rust-toolchain@stable
     - name: Build
       run: cargo build --verbose
     - name: Run tests