chore(ci): bump checkout to v5 (Node 24) – cherry-pick upstream #89

FSoft-AI4Code/CodeWiki#89 bumped checkout@v4->v5 and setup-python@v5->v6 for Node 20 EOL.
Apply checkout bump to CodeWiki-Plus (setup-uv already v6).
Also remove tracked .DS_Store (now .gitignore'd at .gitignore:77).

No input changes; fetch-depth and runner support unchanged (Node 24 requires runner v2.327.1+).

Author: LiberiFatali

.DS_Store

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 20
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
         with:
           fetch-depth: 0
 
@@ -34,7 +34,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 10
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
         with:
           fetch-depth: 0