Fix username

.github/workflows/update_leaderboard_after_merge.yaml

@@ -12,18 +12,17 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
 
-      - name: Get merged commit hash
-        id: merged_commit
+      - name: Get merge commit hash
+        id: merge_commit
         run: |
-          merged_commit=$(git show --format=%H -s $GITHUB_SHA)
-          echo "Merged commit $GITHUB_SHA"
-          echo "::set-output name=merged_commit::$merged_commit"
+          merge_commit=$(git log --merges --pretty=format:%H -1 $GITHUB_SHA)
+          echo "::set-output name=merge_commit::$merge_commit"
 
-      - name: Get author's name from merged commit
-        id: author_name
+      - name: Get second-to-last author's name
+        id: second_last_author_name
         run: |
-          author_name=$(git show -s --format='%ae' ${{ steps.merged_commit.outputs.merged_commit }})
-          echo "::set-output name=author_name::$author_name"
+          second_last_author_name=$(git log --format='%an' -n 2 ${{ steps.merge_commit.outputs.merge_commit }} | tail -n 1)
+          echo "::set-output name=second_last_author_name::$second_last_author_name"
 
       - name: Print author's name
         run: echo "${{ steps.author_name.outputs.author_name }}"