Update coverage script (#429)

* update github action coverage script

.github/workflows/post-merge.yml

@@ -50,7 +50,11 @@ jobs:
               rm ./ci/coverage_threshold.txt
               cp ./ci/coverage_threshold_temp.txt ./ci/coverage_threshold.txt
               git config user.name "github-actions[bot]"
-              git config user.email "github-actions[bot]@users.noreply.github.com"            
+              git config user.email "github-actions[bot]@users.noreply.github.com"
+              git clone https://github.com/rdkcentral/Ripple.git
+              cd Ripple
+              git fetch
+              git checkout locked_actions_branch          
               git add ./ci/coverage_threshold.txt
               git commit -m "chore: git bot update threshold"
               git fetch