Change the depth to 0

Signed-off-by: Shreeya Patel <spatel@ciq.com>

Author: shreeya-patel98

.github/workflows/kernel-build-and-test-x86_64.yml

@@ -205,7 +205,7 @@ jobs:
     - name: Checkout kernel source
       uses: actions/checkout@v4
       with:
-        fetch-depth: 400  # Increased depth for reliable merge-base detection after rebasing
+        fetch-depth: 0  # Full history needed for reliable merge-base detection
 
     - name: Download current kselftest logs
       uses: actions/download-artifact@v4