chore(ci): add update-lockfiles automation wf

.github/workflows/update_lockfiles.yml

@@ -0,0 +1,118 @@
+name: Update lockfiles
+
+on:
+  workflow_dispatch:
+  schedule:
+    - cron: "0 4 * * 1"
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  update-lockfiles:
+    name: Refresh mix.lock files
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    steps:
+      - name: Get auth token
+        id: token
+        uses: actions/create-github-app-token@5d869da34e18e7287c1daad50e0b8ea0f506ce69 # v1.11.0
+        with:
+          app-id: ${{ vars.SENTRY_RELEASE_BOT_CLIENT_ID }}
+          private-key: ${{ secrets.SENTRY_RELEASE_BOT_PRIVATE_KEY }}
+
+      - name: Check out this repository
+        uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6
+        with:
+          token: ${{ steps.token.outputs.token }}
+
+      - name: Setup Elixir and Erlang
+        uses: erlef/setup-beam@fc68ffb90438ef2936bbb3251622353b3dcb2f93 # v1.24.0
+        with:
+          elixir-version: "1.18"
+          otp-version: "27.2"
+
+      - name: Refresh lockfiles
+        run: |
+          for lock in mix.lock test_integrations/*/mix.lock; do
+            dir=$(dirname "$lock")
+            echo "==> Refreshing mix.lock in $dir"
+            (cd "$dir" && mix deps.update --all)
+          done
+
+      - name: Configure git
+        run: |
+          git config user.name 'github-actions[bot]'
+          git config user.email '41898282+github-actions[bot]@users.noreply.github.com'
+
+      - name: Create branch
+        id: create-branch
+        run: |
+          # Stage first, then diff the index against HEAD: plain `git diff` ignores
+          # untracked files, so a brand-new project's lock would look unchanged.
+          git add mix.lock 'test_integrations/*/mix.lock'
+
+          if git diff --cached --quiet; then
+            echo "No lockfile changes; nothing to do."
+            echo "changed=false" >> "$GITHUB_OUTPUT"
+            exit 0
+          fi
+
+          COMMIT_TITLE="chore(deps): Refresh mix.lock files"
+          BRANCH_NAME="deps/lockfiles-update-$(date +%Y-%m-%d)"
+
+          git checkout -B "$BRANCH_NAME"
+          git commit -m "$COMMIT_TITLE"
+          git push origin "$BRANCH_NAME" --force
+
+          echo "changed=true" >> "$GITHUB_OUTPUT"
+          echo "branch_name=$BRANCH_NAME" >> "$GITHUB_OUTPUT"
+          echo "commit_title=$COMMIT_TITLE" >> "$GITHUB_OUTPUT"
+
+      - name: Create pull request
+        if: steps.create-branch.outputs.changed == 'true'
+        uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # v9.0.0
+        env:
+          BRANCH_NAME: ${{ steps.create-branch.outputs.branch_name }}
+          COMMIT_TITLE: ${{ steps.create-branch.outputs.commit_title }}
+        with:
+          github-token: ${{ steps.token.outputs.token }}
+          script: |
+            const branchName = process.env.BRANCH_NAME;
+            const commitTitle = process.env.COMMIT_TITLE;
+            const prBody = `Automated weekly refresh of the committed \`mix.lock\` files via \`mix deps.update --all\`, keeping dependency pins current with the latest security patches allowed by each project's version constraints.
+
+            #skip-changelog
+
+            ## Action required
+            - If CI passes on this PR, it's safe to approve and merge.
+            - If CI fails, a dependency update broke something — investigate before merging.
+
+            _🤖 Automatically created by [.github/workflows/update_lockfiles.yml](https://github.com/getsentry/sentry-elixir/blob/master/.github/workflows/update_lockfiles.yml)._`.replace(/^ {12}/gm, '');
+
+            // Close superseded lockfile PRs — they're now obsolete.
+            const existingPRs = await github.paginate(github.rest.pulls.list, {
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              state: 'open',
+            });
+            for (const pr of existingPRs) {
+              if (pr.head.ref.startsWith('deps/lockfiles-update-')) {
+                await github.rest.pulls.update({
+                  owner: context.repo.owner,
+                  repo: context.repo.repo,
+                  pull_number: pr.number,
+                  state: 'closed',
+                });
+              }
+            }
+
+            await github.rest.pulls.create({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              title: commitTitle,
+              head: branchName,
+              base: 'master',
+              body: prBody,
+            });