Improve backport job permissions

Author: cdce8p

.github/workflows/backport.yml

@@ -6,14 +6,14 @@ on:
       - labeled
 
 permissions:
-  actions: write
-  contents: write
-  pull-requests: write
+  contents: read
 
 jobs:
   backport:
     name: Backport
     runs-on: ubuntu-latest
+    environment:
+      name: Backport
     # Only react to merged PRs for security reasons.
     # See https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#pull_request_target.
     if: >
@@ -27,4 +27,4 @@ jobs:
     steps:
       - uses: tibdex/backport@9565281eda0731b1d20c4025c43339fb0a23812e # v2.0.4
         with:
-          github_token: ${{ secrets.GITHUB_TOKEN }}
+          github_token: ${{ secrets.BACKPORT_TOKEN }}