[CI] Fix by-code-owner labelling (#9661)

.github/workflows/auto-label-pr.yml

@@ -305,8 +305,7 @@ jobs:
               const { data: codeownersFile } = await github.rest.repos.getContent({
                 owner,
                 repo,
-                path: '.github/CODEOWNERS',
-                ref: context.payload.pull_request.head.sha
+                path: 'CODEOWNERS',
               });
 
               const codeownersContent = Buffer.from(codeownersFile.content, 'base64').toString('utf8');