feat: Add pull request trigger to CI/CD pipeline

Include pull request events to trigger the CI/CD pipeline when
modifications are made to the pipeline configuration file. This
ensures changes are validated before merging into the main branch.

.github/workflows/ci-cd-pipeline.yml

@@ -13,6 +13,10 @@ on:
     branches: [main]
     tags: ["v*"]
   workflow_dispatch:
+  pull_request:
+    branches: [main]
+    paths:
+      - .github/workflows/ci-cd-pipeline.yml
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}