hbd feeds.conf: use 23.05 instead of master

In the past few days I have been working on getting hbd switched to 23.05 and to finally start building, some of those commits were merged to hbd and some are just in burstlab. burstlab currently builds only core of Turris OS for Omnia and Turris 1.x, but since hbd has not been building for any boards, I think we should move 23.05 to hbd now so we have a more static target to fix packages for.