fix submod

Author: jsjoeio

.github/workflows/build.yaml

@@ -86,7 +86,7 @@ jobs:
       - name: Get submodule hash
         id: submodule-hash
         run: |
-          echo "::set-output name=key::$(git ls-tree HEAD lib/vscode)"
+          echo "::set-output name=key::$(git ls-tree HEAD lib/vscode --object-only)"
 
       - name: Fetch submodule from cache
         id: cache-submodule