Release test for Yocto LTS opensource releases

Following steps can be used to verify the opensourced LTS release in a Yocto build once it's made public.

1) Normally initialize build env with repo using the corresponding lts manifest

repo init -u git://code.qt.io/yocto/boot2qt-manifest -b master -m v6.2.6-lts.xml
repo sync

2) for meta-qt6, checkout the just released opensource tag

cd sources/meta-qt6
git checkout v6.2.6-lts-lgpl 

3) Follow normal BYOS test steps and build the qbsp

export MACHINE=imx8qm-mek
. ./setup-environment.sh
bitbake meta-b2qt-embedded-qbsp

This needs to be done only with one target machine.