packaging: attempt to fix broken ci because of last commit

The hash for client-uwp from last commit doesn't seem to exist on the
server, thus causing problems.

Change-Id: Id3ef70cc87a4326de2afbe6d5aefed470c4721f4

client-uwp @ 4b639e9a

-Subproject commit 7c248e9d48ee899ad58156e9cc92e4cc4a02f6bc
+Subproject commit 4b639e9a903931bab09292b4d93a4de6d531ae4c