Added changelog reminder (#184)

Adds a workflow that automatically reminds contributors to update the
changelog by commenting on pull requests that lack changelog entries.

Author: snejus

.github/workflows/changelog_reminder.yaml

@@ -0,0 +1,36 @@
+name: Verify changelog updated
+
+on:
+  pull_request_target:
+    types:
+      - opened
+      - ready_for_review
+
+jobs:
+  check_changes:
+    permissions: 
+        pull-requests: write
+        contents: read
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5
+
+      - name: Get all updated Python files
+        id: changed-python-files
+        uses: tj-actions/changed-files@v46
+        with:
+          files: |
+            **.py
+
+      - name: Check for the changelog update
+        id: changelog-update
+        uses: tj-actions/changed-files@v46
+        with:
+          files: docs/changelog.rst
+
+      - name: Comment under the PR with a reminder
+        if: steps.changed-python-files.outputs.any_changed == 'true' && steps.changelog-update.outputs.any_changed == 'false'
+        uses: thollander/actions-comment-pull-request@v2
+        with:
+          message: 'Thank you for the PR! The changelog has not been updated, so here is a friendly reminder to check if you need to add an entry.'
+          GITHUB_TOKEN: '${{ secrets.GITHUB_TOKEN }}'

docs/changelog.rst

@@ -1,6 +1,11 @@
 Changelog
 ---------
 
+v2.1.1
+''''''
+
+- Include `docs` and `tests` directory in source distributions.
+
 v2.1.0
 ''''''
 

docs/dev.rst

@@ -21,3 +21,6 @@ To create a new version, follow these steps:
 3. Refresh the page to see the status of the workflow.
 4. Once it succeeds, create a GitHub release with notes from the
    ``docs/changelog.rst`` file.
+
+Note: This workflow does not update the changelog version numbers; this must be
+done manually before running the release workflow.