基于GithubActions，实现分支代码自动拉取合并

## 起因

想要实现一个开源记账软件的多数据切换，但由于 prisma 不提供线上环境的数据库切换功能，因为该框架构建时会基于不同的数据库构建不同的底层支持，所以打包时必须明确一种数据库。

为了适配 prisma 同时实现多数据库，决定采用多个分支管理代码的方式，每一个分支对应一种数据库方案，这样就可以实现多数据库同步维护，但每次修改代码，每个分支都要同步合并代码，手动管理太过麻烦，因此决定通过 Github Actions 的方式，每次主分支提交代码，通过工作流自动将代码合并到其他分支，大大降低了手动维护成本！

## 示例

下面是老狗的一个 [开源软件](https://github.com/dingdangdog/cashbook) 中正在使用的 `Github Acitons` 配置文件：

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```yaml
name: Auto Sync Branches

on:
  push:
    branches:
      - main

# 添加必要的权限
permissions:
  contents: write
  actions: read

jobs:
  sync-branches:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout main branch
        uses: actions/checkout@v4
        with:
          ref: main
          fetch-depth: 0 # 获取完整历史记录
          token: ${{ secrets.MERGE_TOKEN }}

      - name: Configure Git
        run: |
          git config --global user.name "github-actions[bot]"
          git config --global user.email "github-actions[bot]@users.noreply.github.com"

      - name: Sync to main-mysql branch
        run: |
          echo "Syncing to main-mysql branch..."
          git checkout main-mysql || git checkout -b main-mysql
          git merge main --no-edit || {
            echo "Merge conflict detected for main-mysql, manual intervention required"
            exit 1
          }
          git push origin main-mysql

      - name: Sync to main-pgsql branch
        run: |
          echo "Syncing to main-pgsql branch..."
          git checkout main-pgsql || git checkout -b main-pgsql
          git merge main --no-edit || {
            echo "Merge conflict detected for main-pgsql, manual intervention required"
            exit 1
          }
          git push origin main-pgsql

      - name: Sync to main-sqlite branch
        run: |
          echo "Syncing to main-sqlite branch..."
          git checkout main-sqlite || git checkout -b main-sqlite
          git merge main --no-edit || {
            echo "Merge conflict detected for main-sqlite, manual intervention required"
            exit 1
          }
          git push origin main-sqlite

      - name: Sync to main-sqlserver branch
        run: |
          echo "Syncing to main-sqlserver branch..."
          git checkout main-sqlserver || git checkout -b main-sqlserver
          git merge main --no-edit || {
            echo "Merge conflict detected for main-sqlserver, manual intervention required"
            exit 1
          }
          git push origin main-sqlserver

      - name: Summary
        run: |
          echo "✅ Successfully synced main branch to all database branches:"
          echo "   - main-mysql"
          echo "   - main-pgsql" 
          echo "   - main-sqlite"
          echo "   - main-sqlserver"
```