github: Update action to upload-artifact@v4

upload-artifact@v2 is gone now, so update to v4.

Signed-off-by: Rob Herring (Arm) <[email protected]>

Author: robherring

.github/workflows/ci.yml

@@ -39,7 +39,7 @@ jobs:
       run: make singlehtml
 
     - name: upload
-      uses: actions/upload-artifact@v2
+      uses: actions/upload-artifact@v4
       with:
         name: artifacts
         path: |