ci: Work around reuse-tool regression
https://git.fsfe.org/reuse/tool/commit/5895f3682ba09ced99 marked "QT Creator's UI files" as "uncommentable", which unfortunately applies to GtkBuilder's UI files as well.
As a result, all .ui files are now considered non-compliant, simply because the tool refuses to read the perfectly fine copyright information.
Work around this by patching out the offending line, so the tool processes the files normally again.