Update gemini-pr-review.yml

Author: richabanker

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

@@ -25,9 +25,8 @@ jobs:
       - name: Get PR diff
         id: diff
         run: |
-          echo "DIFF<<EOF" >> $GITHUB_OUTPUT
-          git diff origin/${{ github.event.pull_request.base.ref }} ${{ github.sha }} >> $GITHUB_OUTPUT
-          echo "EOF" >> $GITHUB_OUTPUT
+         gh pr diff ${{ github.event.pull_request.number }} > diff.txt
+         echo "DIFF=$(cat diff.txt)" >> $GITHUB_OUTPUT
       
       - name: Debug diff output
         run: echo "${{ steps.diff.outputs.DIFF }}"