improve[ci]: standardize the naming of CI files related to auto assign reviewers

Author: kurisaW

…thub/workflows/auto-assign-reviewers.yml …thub/workflows/auto_assign_reviewers.yml.github/workflows/auto-assign-reviewers.yml renamed to .github/workflows/auto_assign_reviewers.yml .github/workflows/auto-assign-reviewers.yml renamed to .github/workflows/auto_assign_reviewers.yml

@@ -461,4 +461,4 @@ jobs:
           path: |
             unique_tags_bak.txt
             unique_reviewers_bak.txt
-          key: ${{ runner.os }}-auto-assign-reviewers-${{ steps.extract-pr.outputs.PR_NUMBER }}-${{ steps.get_comment_time.outputs.CACHE_TIMESTAMP }}-${{ github.run_id }}
+          key: ${{ runner.os }}-auto-assign-reviewers-${{ steps.extract-pr.outputs.PR_NUMBER }}-${{ steps.get_comment_time.outputs.CACHE_TIMESTAMP }}-${{ github.run_id }}