Github action workflow to run build for PR

.github/workflows/clrt.yaml

@@ -8,6 +8,9 @@ on:
       - '[0-9][0-9][0-9][0-9].[0-9][0-9].*' # 2021.01.x
     tags:
       - '[0-9][0-9][0-9][0-9].[0-9][0-9].[0-9][0-9]' # 2021.01.01
+  pull_request:
+    branches:
+      - main
 
   workflow_dispatch:
     inputs:
@@ -28,9 +31,13 @@ jobs:
       - name: Checkout code 
         uses: actions/checkout@v4
 
-      - name: Extract branch name
-        id: extract_branch
-        run: echo "BRANCH_NAME=$(basename ${{ github.ref }})" >> $GITHUB_ENV
+      - name: Extract branch or PR number
+        id: extract_branch_or_pr
+        run: |
+          if [[ "${{ github.event_name }}" == "pull_request" ]]; then
+            echo "BRANCH_OR_PR=pr-${{ github.event.number }}" >> $GITHUB_ENV
+          else
+            echo "BRANCH_OR_PR=$(basename ${{ github.ref }})" >> $GITHUB_ENV
       
       - name: build Docker image
         run: |