qt6_tool.py: Adapt to qtwebengine branching


Change-Id: Id1f770fccf67f79ea5ded11a6e7b5f42b83ece70
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
commit485a0e7e802698c567febdacbedc6670674d972d
parent2c41b5303ffb7dde77b1c7ce8ed48bb8c8efb1e1
authorFriedemann Kleint <Friedemann.Kleint@qt.io>
committerFriedemann Kleint <Friedemann.Kleint@qt.io>
commit timeTue, 20 Oct 2026 12:29:10 +0000