add extra_info field to APTUpdateInfo

Add an optional string field to APTUpdateInfo which can be used for
extra information.

This is used for passing running kernel and running version information
in the versions API call together with proxmox-backup and
proxmox-backup-server.

Signed-off-by: Mira Limbeck <m.limbeck@proxmox.com>

src/tools/apt.rs

@@ -361,6 +361,7 @@ where
                 },
                 priority: priority_res,
                 section: section_res,
+                extra_info: None,
             });
         }
     }