Use the annotated tag message for release body

.github/workflows/publish-release.yml

@@ -22,6 +22,14 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           pip install --upgrade setuptools wheel twine
+      - name: Get release notes
+        id: release_notes
+        run: |
+          CHANGELOG=$(git tag -l --format='%(contents)' ${{ github.ref }})
+          CHANGELOG="${CHANGELOG//'%'/'%25'}"
+          CHANGELOG="${CHANGELOG//$'\n'/'%0A'}"
+          CHANGELOG="${CHANGELOG//$'\r'/'%0D'}"
+          echo "::set-output name=changelog::$CHANGELOG"
       - name: Create GitHub release
         id: create_release
         uses: actions/create-release@v1
@@ -30,8 +38,7 @@ jobs:
         with:
           tag_name: ${{ github.ref }}
           release_name: ${{ github.ref }}
-          body: |
-            Please see the root of the repository for the CHANGELOG.md
+          body: ${{ steps.release_notes.outputs.changelog }}
           draft: false
           prerelease: false
       - name: Build and publish to PyPI