Hotfix/migrate3x 1x invalid branch

The original reason and also temporally fix (before 5.1 release) is https://gitlab.labs.nic.cz/turris/turris-os-packages/issues/606

changed milestone to %Turris OS 5.0.1

added Bug High labels

Simple change and I take a look at it. It's fine. I like that we will migrate users to HBS instead of HBK.

Well in reality it is just about what branch is used to get new version of updater. Target branch is later determined by script from tos3to4 package.

assigned to @kkoci and unassigned @jschlehofer

merged

mentioned in issue turris-os-packages#344