Fix publishing

Author: umbrellait-timur-khismatullin

.github/workflows/publish.yml

@@ -1,10 +1,11 @@
 name: publish
 
 on:
-  push:
+  pull_request:
+    types: [closed]
     branches:
       - master
-
+      
 jobs:
   publish:
     timeout-minutes: 4
@@ -28,7 +29,7 @@ jobs:
         id: pubspec
         run: |
           set +e
-          git diff-tree --no-commit-id --name-only -r ${{ github.sha }} | grep '${{ matrix.package }}/pubspec.yaml'
+          git diff-tree --no-commit-id --name-only -r HEAD~1 ${{ github.sha }} | grep '${{ matrix.package }}/pubspec.yaml'
           echo ::set-output name=changed::$?
           set -e
       - name: Extract package version