Add repository checkout to CompatHelper workflow to prevent duplicate PRs

[Copilot]

CompatHelper is creating duplicate PRs daily because it cannot detect existing compathelper/* branches without a repository checkout. Without access to the repo state, each cron run opens new PRs for the same compat updates (currently up to PR #448+).

Changes

• Added actions/checkout@v4 as the first workflow step

steps:
  - name: Check out repository
    uses: actions/checkout@v4
  - name: Pkg.add("CompatHelper")
    run: julia -e 'using Pkg; Pkg.add("CompatHelper")'
  - name: CompatHelper.main()
    # ... rest unchanged

This allows CompatHelper to inspect existing branches and skip opening duplicate PRs.

Original prompt

Problem

The CompatHelper GitHub Actions workflow is creating duplicate PRs every single day for the same package compat updates. For example, the same set of ~19 compat updates (DifferentialEquations, Jutul, JutulDarcy, SpecialFunctions, Roots, Literate, Interpolations, etc.) are being opened as new PRs on every cron run, leading to hundreds of duplicate PRs (currently up to PR #448+).

Root Cause

The workflow at .github/workflows/CompatHelper.yml is missing a repository checkout step. Without checking out the repo, CompatHelper cannot inspect existing branches (named like compathelper/...) to detect that a PR for the same compat update is already open, causing it to create duplicates every run.

Current workflow

name: CompatHelper
on:
  schedule:
    - cron: 0 0 * * *
  workflow_dispatch:
jobs:
  CompatHelper:
    runs-on: ubuntu-latest
    steps:
      - name: Pkg.add("CompatHelper")
        run: julia -e 'using Pkg; Pkg.add("CompatHelper")'
      - name: CompatHelper.main()
        env:
          GITHUB_TOKEN: ${{ secrets.CompatHelperTokenPrivateRepos }}
          COMPATHELPER_PRIV: ${{ secrets.DOCUMENTER_KEY }}
        run: julia -e 'using CompatHelper; CompatHelper.main()'

Required Fix

Add an actions/checkout@v4 step before the CompatHelper steps so the tool can detect existing branches and open PRs:

name: CompatHelper
on:
  schedule:
    - cron: 0 0 * * *
  workflow_dispatch:
jobs:
  CompatHelper:
    runs-on: ubuntu-latest
    steps:
      - name: Check out repository
        uses: actions/checkout@v4
      - name: Pkg.add("CompatHelper")
        run: julia -e 'using Pkg; Pkg.add("CompatHelper")'
      - name: CompatHelper.main()
        env:
          GITHUB_TOKEN: ${{ secrets.CompatHelperTokenPrivateRepos }}
          COMPATHELPER_PRIV: ${{ secrets.DOCUMENTER_KEY }}
        run: julia -e 'using CompatHelper; CompatHelper.main()'

The only change needed is adding the actions/checkout@v4 step as the first step in the job.

This pull request was created from Copilot chat.

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