Use towncrier to generate release notes (#548)

Author: terencehonles

.github/workflows/ci.yml

@@ -143,3 +143,42 @@ jobs:
         uses: codecov/codecov-action@v1
         with:
           flags: mypy
+
+  check-changelog:
+    name: Check for news fragments in 'changelog.d/'
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+
+      - name: Set up Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: '3.x'
+
+      - name: Get pip cache dir
+        id: pip-cache
+        run: |
+          echo "::set-output name=dir::$(pip cache dir)"
+
+      - name: Cache
+        uses: actions/cache@v2
+        with:
+          path: ${{ steps.pip-cache.outputs.dir }}
+          key: pip-check-changelog-${{ hashFiles('**/setup.*') }}
+          restore-keys: |
+            pip-check-changelog-
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade towncrier
+
+      - name: Run towncrier check
+        run: |
+          if ! towncrier check; then
+            echo ''
+            echo "Please add a description of your changes to 'changelog.d/{issue or PR number}.{feature,bugfix,removal}'"
+            exit 1
+          fi