ci: updates checkout action

Author: rasulomaroff

.github/workflows/ci.yml

@@ -11,7 +11,7 @@ jobs:
       contents: write
     if: ${{ github.ref == 'refs/heads/main' }}
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: panvimdoc
         uses: kdheepak/panvimdoc@main
         with: