[TF-M] Branch release/1.6.x to be deleted

Hi,

Please be aware that the branch release/1.6.xhttps://git.trustedfirmware.org/TF-M/trusted-firmware-m.git/log/?h=release/1.6.x is to be removed, following TF-M release processhttps://tf-m-user-guide.trustedfirmware.org/releases/release_process.html#release-cadence-and-process. Please stop using it by the end of this week (Jan 13) or let me know if more time is necessary.

The previous releases will be still available via tags like TF-Mv1.6.1https://git.trustedfirmware.org/TF-M/trusted-firmware-m.git/tag/?h=TF-Mv1.6.1

Thanks, Anton