qt6_tool: Update handling of branches


qtqa now gets version branches, too. Switch qtrepotools to
master, automatically.

Change-Id: Iabda71551a1332c485ea131ce291334208d4cf42
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
commitc29a3c2801d99b128ab68aab6a829d96c231d281
parentb00189c52d20b472ae4209ef18f20dbe5eea81ce
authorFriedemann Kleint <Friedemann.Kleint@qt.io>
committerFriedemann Kleint <Friedemann.Kleint@qt.io>
commit timeMon, 4 Nov 2024 10:04:49 +0000