[batch-release] Step3: Adds github action to create a PR to sync changes on the release branch back to the main branch

[hannah-hyj]

issue: #177110
Everytime something is pushed to the release branch, sync it back to the main branch.

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[gemini-code-assist]

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[chunhtai]

There is existing github action

     - name: Create Pull Request
        uses: peter-evans/create-pull-request@v7
        with:
          token: ${{ secrets.GITHUB_TOKEN }}
          commit-message: "...."
          title: "...."
          body: "...."
          branch: release
          base: main

[stuartmorgan-g]

Wait, I'm confused about the flow again. How can there be a single release branch that multiple packages are doing releases from while still supporting the async PR approval model? The whole point of using a branch for a release is that the branch can be a snapshot of the state that we want to release for a given package version.

@chunhtai is there a diagram or flow chart in a doc somewhere that shows the final plan for how the branches will work?

[chunhtai]

ah, I forgot about the race condition if we use single branch, where the other package may have merged and brought in new changes.

yeah.. in that case you would need separate release branch for each packages. let me revise the doc a bit and update the issues

[chunhtai]

https://docs.google.com/document/d/1jUoFaawutbYsCI5oY3pDP_l-xpv6FhDKlcI1-EoT02s/edit?tab=t.0