update env for PR pipelines

.github/workflows/pr_backend.yml

@@ -16,7 +16,7 @@ jobs:
     strategy:
       matrix:
         python-version: ['3.10']
-    environment: Staging
+    environment: PR
     steps:
       - name: Checkout source
         uses: actions/checkout@v4

.github/workflows/pr_frontend.yml

@@ -1,13 +1,12 @@
 name: Pull Request Frontend
 on:
   push:
-    branches: [main]
     paths:
       - "client/**/*"
 jobs:
   build:
     runs-on: ubuntu-latest
-    environment: Staging
+    environment: PR
     defaults:
       run:
         working-directory: client