Update circleci.yml

.github/workflows/circleci.yml

@@ -4,19 +4,12 @@ on:
   push:
     branches:
     - main
-  pull_request_target:
+  pull_request:
     branches:
     - main
 jobs:
-  approve: # First step
-    runs-on: ubuntu-latest
-    steps:
-    - name: Approve
-      run: echo For security reasons, all pull requests need to be approved first before running any automated CI.
   trigger-circleci:
     runs-on: ubuntu-latest
-    environment: 'ci'
-    needs: [approve] # Require the first step to finish
     steps:
       - name: secretflow-yacl-ci
         id: secretflow-yacl-ci