add firehose workflow (#1228)

* add firehose workflow

* format the changelog how firehose wants

Author: jakemac53

.github/workflows/publish.yml

@@ -0,0 +1,14 @@
+# A CI configuration to auto-publish pub packages.
+
+name: Publish
+
+on:
+  pull_request:
+    branches: [ main ]
+    types: [opened, synchronize, reopened, labeled, unlabeled]
+  push:
+    tags: [ 'v[0-9]+.[0-9]+.[0-9]+' ]
+
+jobs:
+  publish:
+    uses: dart-lang/ecosystem/.github/workflows/publish.yaml@main