Address review: fix _toc.yml path, bump checkout to v6

Author: mmcky

.github/workflows/sync-translations-fa.yml

@@ -7,15 +7,15 @@ on:
     types: [closed]
     paths:
       - 'lectures/**/*.md'
-      - '_toc.yml'
+      - 'lectures/_toc.yml'
 
 jobs:
   sync:
     if: github.event.pull_request.merged == true
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           fetch-depth: 2