Release workflow

Creates a GH release, but in draft mode because the current action can't
get the git tag message as body.

Closes #226

.github/workflows/release.yml

@@ -0,0 +1,25 @@
+on:
+  push:
+    tags:
+      - 'v*' # Push events to matching v*, i.e. v1.0, v20.15.10
+
+name: Create Release
+
+jobs:
+  build:
+    name: Create Release
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+      - name: Create Release
+        id: create_release
+        uses: actions/create-release@v1
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }} # This token is provided by Actions, you do not need to create your own token
+        with:
+          tag_name: ${{ github.ref }}
+          release_name: ${{ github.ref }}
+          body_path: CHANGELOG.md
+          draft: true
+          prerelease: false