Update push main notification card

.github/workflows/push_notification.yml

@@ -8,6 +8,8 @@ on:
 jobs:
   notify-push-main:
     runs-on: ubuntu-latest
+    env:
+      COMMIT: ${{ github.event.head_commit.message }}
     steps:
     - name: Main Branch Push
       run: |
@@ -24,7 +26,7 @@ jobs:
             {
               "header": {
                 "title": "Push to main branch",
-                "subtitle": "${{ github.event.head_commit.message }}"
+                "subtitle": "$COMMIT"
               },
               "sections": [
                 {