Update trigger-deploy-on-merge.yml (#86)

Trigger only on pull request merge
This pull request makes a small change to the deployment workflow,
ensuring that the `deploy-frontend` job only runs when a pull request is
merged.

* Added a conditional (`if: github.event.pull_request.merged == true`)
to the `deploy-frontend` job in
`.github/workflows/trigger-deploy-on-merge.yml` to prevent deployments
on unmerged pull requests.

Author: susrisha

.github/workflows/trigger-deploy-on-merge.yml

@@ -9,6 +9,7 @@ permissions:
 
 jobs:
     deploy-frontend:
+        if: github.event.pull_request.merged == true
         runs-on: ubuntu-latest
         env:
             GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}