fix: grant write permissions to GITHUB_TOKEN for CML job

.github/workflows/train.yml

@@ -9,6 +9,9 @@ on:
 jobs:
   train-and-report:
     runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      pull-requests: write
     steps:
     - name: Checkout repository
       uses: actions/checkout@v4