Install Python in update-bundle workflow

.github/workflows/script/bundle_changelog.py

@@ -0,0 +1,18 @@
+import os
+import re
+
+# Get the PR number from the PR URL.
+pr_number = os.environ['PR_URL'].split('/')[-1]
+changelog_note = f"- Update default CodeQL bundle version to {os.environ['CLI_VERSION']}. [#{pr_number}]({os.environ['PR_URL']})"
+
+# If the "[UNRELEASED]" section starts with "no user facing changes", remove that line.
+with open('CHANGELOG.md', 'r') as f:
+    changelog = f.read()
+
+changelog = changelog.replace('## [UNRELEASED]\n\nNo user facing changes.', '## [UNRELEASED]\n')
+
+# Add the changelog note to the bottom of the "[UNRELEASED]" section.
+changelog = re.sub(r'\n## (\d+\.\d+\.\d+)', f'{changelog_note}\n\n## \\1', changelog, count=1)
+
+with open('CHANGELOG.md', 'w') as f:
+    f.write(changelog)

.github/workflows/update-bundle.yml

@@ -40,6 +40,11 @@ jobs:
           git config --global user.email "41898282+github-actions[bot]@users.noreply.github.com"
           git config --global user.name "github-actions[bot]"
 
+      - name: Set up Python
+        uses: actions/setup-python@v6
+        with:
+          python-version: '3.12'
+
       - name: Set up Node.js
         uses: actions/setup-node@v6
         with:
@@ -78,28 +83,8 @@ jobs:
           echo "PR_URL=$pr_url" | tee -a "$GITHUB_ENV"
 
       - name: Create changelog note
-        shell: python
         run: |
-          import os
-          import re
-
-          # Get the PR number from the PR URL.
-          pr_number = os.environ['PR_URL'].split('/')[-1]
-          changelog_note = f"- Update default CodeQL bundle version to {os.environ['CLI_VERSION']}. [#{pr_number}]({os.environ['PR_URL']})"
-
-          # If the "[UNRELEASED]" section starts with "no user facing changes", remove that line.
-          # Use perl to avoid having to escape the newline character.
-
-          with open('CHANGELOG.md', 'r') as f:
-              changelog = f.read()
-
-          changelog = changelog.replace('## [UNRELEASED]\n\nNo user facing changes.', '## [UNRELEASED]\n')
-
-          # Add the changelog note to the bottom of the "[UNRELEASED]" section.
-          changelog = re.sub(r'\n## (\d+\.\d+\.\d+)', f'{changelog_note}\n\n## \\1', changelog, count=1)
-
-          with open('CHANGELOG.md', 'w') as f:
-              f.write(changelog)
+          python .github/workflows/script/bundle_changelog.py
 
       - name: Push changelog note
         run: |