build_wamr_vscode_ext.yml: vsce publish only on the official repo (#2130)

This makes it simpler to test workflow files on a fork.

.github/workflows/build_wamr_vscode_ext.yml

@@ -32,13 +32,16 @@ jobs:
         working-directory: test-tools/wamr-ide/VSCode-Extension
 
       - name: generate wamr ide vscode extension
-        env:
-          credentials: ${{ secrets.TOKEN }}
         run: |
           npm install -g vsce
           rm -rf node_modules
           npm install
           vsce package
+        working-directory: test-tools/wamr-ide/VSCode-Extension
+
+      - name: publish wamr ide vscode extension to the vsce marketplace
+        if: ${{ github.repository == 'bytecodealliance/wasm-micro-runtime' }}
+        run: |
           vsce publish -p ${{ secrets.TOKEN }}
         working-directory: test-tools/wamr-ide/VSCode-Extension