Update gemini-pr-review.yml

Author: richabanker

.github/workflows/gemini-pr-review.yml

@@ -24,6 +24,8 @@ jobs:
 
       - name: Get PR diff
         id: diff
+        env:
+          GH_TOKEN: ${{ github.token }}
         run: |
          gh pr diff ${{ github.event.pull_request.number }} > diff.txt
          echo "DIFF=$(cat diff.txt)" >> $GITHUB_OUTPUT