update_submodules.yml

name: Update submodules
run-name: Update submodules
permissions: write-all
on:
  schedule:
    - cron:  '0 0 * * *'
  workflow_dispatch:
  push:
    branches:
      - main

jobs:
  update_submodules:
    name: Update submodules
    runs-on: ubuntu-latest
    env:
      TZ: "Asia/Tokyo"
    if: contains(github.event.head_commit.message, '[ci skip]') == false
    steps:
    - uses: actions/checkout@v2
      with:
        submodules: recursive
    - name: Update submodules
      id: update
      run: git submodule update --remote --recursive 
    - name: Run git status
      id: status
      run: echo "::set-output name=status::$(git status -s)"
    - name: Add and commit files
      run: |
        git add .
        git config --local user.email "action@github.com"
        git config --local user.name "GitHub Action"
        git commit -m "Update submodules at $(date "+DATE: %Y-%m-%d TIME: %H:%M:%S")"
      if: ${{ steps.status.outputs.status }}
    - name: Push changes
      uses: ad-m/github-push-action@master
      with:
        github_token: ${{ secrets.GITHUB_TOKEN }}
        branch: main
      if: ${{ steps.status.outputs.status && github.event_name == 'push' }}