Added CD

Author: calvintam236

Diff for: .github/workflows/cd.yml

@@ -0,0 +1,18 @@
+name: cd
+
+on:
+  release:
+    types:
+      - published
+
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+    environment: release
+    steps:
+      - uses: actions/checkout@v2
+      - uses: k-paxian/dart-package-publisher@master
+        with:
+          accessToken: ${{ secrets.OAUTH_ACCESS_TOKEN }}
+          refreshToken: ${{ secrets.OAUTH_REFRESH_TOKEN }}
+          format: true