[ci] Enabled openwisp-utils changelog bot #495

Enabled the new changelog bot which automatically posts
a proposed change log entry as a comment when PRs are approved,
which maintainers can copy/paste when squash merging.

Closes #495

Author: pushpitkamboj

.github/workflows/bot-changelog-runner.yml

@@ -0,0 +1,54 @@
+name: Changelog Bot Runner
+
+on:
+  workflow_run:
+    workflows: ["Changelog Bot Trigger"]
+    types:
+      - completed
+
+permissions:
+  actions: read
+
+jobs:
+  fetch-metadata:
+    runs-on: ubuntu-latest
+    if: github.event.workflow_run.conclusion == 'success'
+    permissions:
+      actions: read
+    outputs:
+      pr_number: ${{ steps.metadata.outputs.pr_number }}
+    steps:
+      - name: Download PR metadata
+        id: download
+        uses: actions/download-artifact@v8
+        with:
+          name: changelog-metadata
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          run-id: ${{ github.event.workflow_run.id }}
+        continue-on-error: true
+
+      - name: Read PR metadata
+        if: steps.download.outcome == 'success'
+        id: metadata
+        run: |
+          PR_NUMBER=$(cat pr_number)
+          if ! [[ "$PR_NUMBER" =~ ^[0-9]+$ ]]; then
+            echo "::error::Invalid PR number: $PR_NUMBER"
+            exit 1
+          fi
+          echo "pr_number=$PR_NUMBER" >> $GITHUB_OUTPUT
+
+  changelog:
+    needs: fetch-metadata
+    if: needs.fetch-metadata.outputs.pr_number != ''
+    permissions:
+      contents: read
+      pull-requests: write
+      issues: write
+    uses: openwisp/openwisp-utils/.github/workflows/reusable-bot-changelog.yml@master
+    with:
+      pr_number: ${{ needs.fetch-metadata.outputs.pr_number }}
+    secrets:
+      GEMINI_API_KEY: ${{ secrets.GEMINI_API_KEY }}
+      OPENWISP_BOT_APP_ID: ${{ secrets.OPENWISP_BOT_APP_ID }}
+      OPENWISP_BOT_PRIVATE_KEY: ${{ secrets.OPENWISP_BOT_PRIVATE_KEY }}

.github/workflows/bot-changelog-trigger.yml

@@ -0,0 +1,38 @@
+name: Changelog Bot Trigger
+
+on:
+  pull_request_review:
+    types: [submitted]
+
+permissions: {}
+
+jobs:
+  check:
+    if: |
+      github.event.review.state == 'approved' &&
+      (github.event.review.author_association == 'OWNER' ||
+        github.event.review.author_association == 'MEMBER' ||
+        github.event.review.author_association == 'COLLABORATOR')
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check for noteworthy PR
+        id: check
+        env:
+          PR_TITLE: ${{ github.event.pull_request.title }}
+        run: |
+          if echo "$PR_TITLE" | grep -qiE '^\[(feature|fix|change)\]'; then
+            echo "has_noteworthy=true" >> $GITHUB_OUTPUT
+          fi
+
+      - name: Save PR metadata
+        if: steps.check.outputs.has_noteworthy == 'true'
+        env:
+          PR_NUMBER: ${{ github.event.pull_request.number }}
+        run: echo "$PR_NUMBER" > pr_number
+
+      - name: Upload PR metadata
+        if: steps.check.outputs.has_noteworthy == 'true'
+        uses: actions/upload-artifact@v7
+        with:
+          name: changelog-metadata
+          path: pr_number