change ci rust version to stable

Author: colmazia

.github/workflows/ci.yaml

@@ -10,6 +10,9 @@ jobs:
 
       - name: Install Rust and rust toolchain
         uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          override: true
 
       - name: Install Wabt (wat2wasm)
         run: |