fix: optimize commit retrieval by converting to CSV format for environment variable

Author: niros1

.github/workflows/reassign-copilot-commits.yml

@@ -44,7 +44,8 @@ jobs:
           GH_TOKEN: ${{ secrets.GH_PAT }}
         run: |
           COMMITS=$(gh pr view $PR_NUMBER --json commits -q '.commits[].oid')
-          echo "COMMITS=$COMMITS" >> $GITHUB_ENV
+          COMMITS_CSV=$(echo "$COMMITS" | paste -sd, -)
+          echo "COMMITS=$COMMITS_CSV" >> $GITHUB_ENV
           echo "$COMMITS" > commits.txt
 
       - name: Check for Copilot as author