chore(CI): intergration checkout if branch existed

fix for integration with topics

log:

.github/workflows/auto-integration-pr.yml

@@ -46,6 +46,7 @@ jobs:
       - name: Install depends for load scripts
         run: |
           npm install js-yaml
+          npm install shelljs
           npm install @octokit/rest
           npm install @octokit/auth-app
 
@@ -137,6 +138,12 @@ jobs:
               auotintegrationbranch = "topic-auto-integration-" + topic
             }
 
+            // checkout the branch if it existed
+            const shell = require('shelljs')
+            if (shell.exec(`git checkout ${auotintegrationbranch}`).code !== 0) {
+              console.log(auotintegrationbranch, " not existed, use master branch")
+            }
+
             // genarate integration.yml
             const yaml = require('js-yaml')
             const fs = require('fs')