[bug] Probot throws error trying to squash and merge, when you can do it on Github UI

Bug Report

Current Behavior A clear and concise description of the behavior.

  // Your code here
await github.pullRequests.merge(
            context.repo({
                number: pullRequest.number,
                commit_title: pullRequest.title,
                commit_message: commitMessage,
                merge_method: 'squash',
            })
        );

Expected behavior/code A clear and concise description of what you expected to happen (or code). The bot should merge the PR with ‘squash’ technique.

What is happening is that the bot is giving this error: Failed to merge PR: You're not authorized to push to this branch. Visit https://help.github.com/enterprise/2.12/user/articles/about-protected-branches/ for more information.

Why is this an issue?

Github allows them to squash and merge from the github UI, so as a consumer of a library, it is unclear why it would give us this error message. I doubt this is an issue in probot, however, not knowing where to create this ticket, I think this is a good place to start.

Environment

• Probot version(s): [e.g. v7.0.0]
• Node/npm version: [e.g. Node 8/npm 5]
• OS: [e.g. Linux]

[welcome[bot]]

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[jbhoosreddy]

Thanks for the info. Really appreciate it.