pin toolchain

Author: jayantk

.github/workflows/ci-sui-contract.yml

@@ -18,6 +18,11 @@ jobs:
         working-directory: target_chains/sui/contracts/
     steps:
       - uses: actions/checkout@v3
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: 1.77.0
+          override: true
       - uses: taiki-e/cache-cargo-install-action@v2
         with:
           tool: sui