Revert "ci: add assign-reviewer job (#529)" (#590)

This reverts commit 675caa0.

.github/workflows/automation.yaml

@@ -24,28 +24,3 @@ jobs:
       - uses: actions/labeler@v5
         with:
           repo-token: ${{ github.token }}
-
-  assign-reviewer:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Get previous PR author and assign as reviewer
-        env:
-          GITHUB_TOKEN: ${{ github.token }}
-        run: |
-          current_repo=${{ github.repository }}
-          current_pr_num=${{ github.event.number }}
-
-          # 이전 PR 중에서 현재 PR 작성자와 다른 작성자 찾기
-          previous_pr_author=$(gh pr list --repo $current_repo \
-            --state all \
-            --search "created:<${{ github.event.pull_request.created_at }} sort:created-desc -author:${{ github.actor }}" \
-            --limit 3 \
-            --json number,author \
-            --jq "map(select(.number < $current_pr_num))[0].author.login")
-          
-          if [ -n "$previous_pr_author" ]; then
-            gh pr edit $current_pr_num --repo $current_repo --add-reviewer $previous_pr_author
-          else
-            echo "❌ No previous PR author found to assign as reviewer"
-            exit 1
-          fi