Dear Maintainer,

Installing `qtqr` does not automatically install the `libqt5multimedia5-plugins` package.
Without this package installed, no cameras are shown (not on my computer anyway).

Perhaps this should be added as at least as a recommend/suggest depend, as it is not so easy to guess that this is the problem.

I looked at the version in sid and it seems to also lack this depend, so I suppose the same will apply for that version.

Thanks for packaging this otherwise excellent tool that I use regularly.