autopkgtest testbed is lacking dpkg-dev and tools like gem2deb relied on their presence without declaring the dependency

Hi,

We have some legacy lack of depends on gem2deb (that lack depends on build-essential). It break autopkgtest on debusine

We plan to fix the build for sid, but does it exist a means to override default depends on existing distrubition to be bug to bug compatible for autopkgtest ?

Feel free to merge or close