update github action to log git diff in output

[rajsinghparihar]

No description provided.

[github-actions]

Summary of Bug Found in Code

Potential Issues and Errors:

• The code changes may cause issues with the Git diff functionality, potentially leading to incorrect or incomplete diff results.
• The introduction of a new environment variable DEFAULT_BRANCH may cause conflicts or unexpected behavior if not properly handled.
• The exclusion of PNG files from the diff may not be intended or may have unintended consequences on the code review process.

Most Important Findings:

• The code has been modified to fetch the default branch instead of the pull request head ref, which may alter the diff results (lines 18-20).
• The git diff command has been updated to exclude PNG files, which may not be the intended behavior (line 21).
• The way the diff result is stored in an environment variable has been changed, using a multi-line string approach (lines 23-26).

Code Block and Line Numbers:

@@ -18,13 +18,20 @@ jobs:
         id: get_diff
         shell: bash
         env:
+          DEFAULT_BRANCH: "${{ github.event.repository.default_branch }}"
           PULL_REQUEST_HEAD_REF: "${{ github.event.pull_request.head.ref }}"
         run: |-
-          git fetch origin "${{ env.PULL_REQUEST_HEAD_REF }}:${{ env.PULL_REQUEST_HEAD_REF }}"
-          git checkout "${{ env.PULL_REQUEST_HEAD_REF }}"
-          git diff "origin/${{ env.PULL_REQUEST_HEAD_REF }}" > "diff.txt"
+          # Fetch the default branch
+          git fetch origin "${{ env.DEFAULT_BRANCH }}"
+          # Exclude png files from diff
+          git diff "origin/${{ env.DEFAULT_BRANCH }}" ":(exclude)*.png" > "diff.txt"
+          # Put multi-line string into an environment variable
           # shellcheck disable=SC2086
-          echo "diff=$(cat "diff.txt")" >> $GITHUB_ENV
+          {
+            echo "pull_request_diff<<EOF";
+            cat "diff.txt";
+            echo 'EOF';
+          } >> $GITHUB_OUTPUT

Lines 18-26 have been modified, introducing changes to the Git diff functionality and environment variable handling.