Remove ability to manual run workflow

Author: microbit-robert

.github/workflows/build-simx.yml

@@ -6,8 +6,6 @@ on:
     tags:
       - v**
 
-  workflow_dispatch:
-
 jobs:
   build:
     runs-on: ubuntu-latest
@@ -29,7 +27,7 @@ jobs:
         working-directory: simx
       - name: github pages
         uses: peaceiris/actions-gh-pages@v3
-        if: ${{ startsWith(github.ref, 'refs/tags/v') || github.ref == 'refs/heads/main' }}
+        if: ${{ startsWith(github.ref, 'refs/tags/v') }}
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           publish_dir: ./simx/dist