Run workflow on PR merge

.github/workflows/update.yml

@@ -1,12 +1,14 @@
 name: Publish Package
 
 on:
-  push:
+  pull_request:
+    types: [closed]
     branches:
       - main
 
 jobs:
   publish:
+    if: github.event.pull_request.merged == true
     runs-on: ubuntu-latest
     steps:
       - name: Checkout code
@@ -29,7 +31,7 @@ jobs:
         run: npm version patch
 
       - name: Push version change
-        run: git push --tags
+        run: git push && git push --tags
 
       - name: Publish to npm
         run: npm publish