fix(workflows): Bump upload action before deprecation (#1956)

Reviewed-by: Alexander Jung <alex@unikraft.io>
Approved-by: Alexander Jung <alex@unikraft.io>

Author: nderjung

.github/workflows/myself-full.yaml

@@ -37,7 +37,7 @@ jobs:
           outputs: type=docker,dest=/tmp/myself.tar
 
       - name: Upload Docker image artifact
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: oci-images
           path: /tmp/myself-full.tar