ci: fetch full history for whitespace checks

Co-Authored-By: Codex <noreply@openai.com>

Author: Pigbibi

.github/workflows/ci.yml

@@ -26,6 +26,8 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
 
       - name: Check whitespace
         run: |