Bump version to 6.12.0


Change-Id: I1edc61de903243f9a02f1a71770896a040e21ba9
Reviewed-by: Akseli Salovaara <akseli.salovaara@qt.io>
commit7cfb9013faa086cf9a6c13f1bb2e16b2005b63ad
parentec29b0723534b1ebcae463811b676a635827036a
authorJani Heikkinen <jani.heikkinen@qt.io>
committerJani Heikkinen <jani.heikkinen@qt.io>
commit timeTue, 16 Dec 2025 07:20:39 +0000