update the publish workflow (#67)

.github/workflows/post_summaries.yaml

@@ -0,0 +1,17 @@
+name: Comment on the pull request
+
+on:
+  # Trigger this workflow after the Publish workflow completes. This workflow
+  # will have permissions to do things like create comments on the PR, even if
+  # the original workflow couldn't.
+  workflow_run:
+    workflows: 
+      - Publish
+    types:
+      - completed
+
+jobs:
+  upload:
+    uses: dart-lang/ecosystem/.github/workflows/post_summaries.yaml@main
+    permissions:
+      pull-requests: write

.github/workflows/publish.yaml

@@ -12,3 +12,5 @@ jobs:
   publish:
     if: ${{ github.repository_owner == 'dart-lang' }}
     uses: dart-lang/ecosystem/.github/workflows/publish.yaml@main
+    with:
+      write-comments: false