Fix None returned for gardenlinux.oci.Podman.pull()

Signed-off-by: Tobias Wolf <[email protected]>
On-behalf-of: SAP <[email protected]>

Author: NotTheEvilOne

src/gardenlinux/oci/podman.py

@@ -201,7 +201,8 @@ def pull(
         if oci_tag is not None:
             kwargs["tag"] = oci_tag
 
-        podman.images.pull(container, **kwargs)
+        image = podman.images.pull(container, **kwargs)
+        return image.id
 
     @PodmanContext.wrap
     def push(