feat(desktop): add a new dependency on KDSingleApplication

will enable merge of the desktop client switch to use external library
for single application enforcement

Signed-off-by: Matthieu Gallien <matthieu.gallien@nextcloud.com>

Author: mgallien

client-qt6/Dockerfile

@@ -64,6 +64,7 @@ RUN \
         libkf6archive-dev \
         extra-cmake-modules \
         qtkeychain-qt6-dev \
+        libkdsingleapplication-qt6-dev \
         libsqlite3-dev \
         qt6-5compat-dev \
 # For cmocka based csync tests