add changelog and workflow to test for entries

.github/workflows/changelog.yml

@@ -0,0 +1,26 @@
+name: Changelog
+
+on:
+  pull_request:
+    types: [labeled, unlabeled, opened, synchronize, reopened]
+
+# Only cancel in-progress jobs or runs for the current workflow
+#   This cancels the already triggered workflows for a specific PR without canceling
+#   other instances of this workflow (other PRs, scheduled triggers, etc) when something
+#   within that PR re-triggers this CI
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  changelog:
+    name: Confirm changelog entry
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: Grep for PR number in CHANGES.rst
+        run: grep -P '\[[^\]]*#${{github.event.number}}[,\]]' CHANGES.rst
+        if: ${{ !contains(github.event.pull_request.labels.*.name, 'no-changelog-entry-needed') }}

CHANGES.rst

@@ -0,0 +1,4 @@
+0.0.4 (unreleased)
+------------------
+
+- added changelog [#36]