add dry run test

.github/workflows/publish-dry-run.yaml

@@ -0,0 +1,22 @@
+name: Publish to pub.dev
+
+on:
+  push:
+    branches:
+      - dry-run-test
+
+# Publish using custom workflow
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: dart-lang/setup-dart@v1
+      - name: Install dependencies
+        run: dart pub get
+      - name: Add version
+        run: |
+          echo "\n\nversion: ${GITHUB_REF_NAME##v}" >> pubspec.yaml
+          cat pubspec.yaml
+      - name: Check Publish Warnings
+        run: dart pub publish --dry-run