Update rust.yml

.github/workflows/rust.yml

@@ -10,6 +10,12 @@ jobs:
     steps:
     - uses: actions/checkout@v1
 
+    - name: Setup rust
+      uses: actions-rs/toolchain@v1
+      with:
+        toolchain: stable
+        override: true
+
     - name: Cache cargo registry
       uses: actions/cache@v1
       with: