[TF-M] TF-M v2.1.6-LTS and v2.3.1-LTS releases announcement

Hello,

We're pleased to announce the release of 2 new TF-M LTS versions: TF-M v2.1.6 and TF-M v2.3.1.

Highlights:

* Upgraded to the latest PSA Crypto and Mbed TLS libraries, including the latest security fixes and advisories * Security fixes identified since the previous releases * Critical bug fixes

For full details please see the release notes:

* v2.1.6: https://trustedfirmware-m.readthedocs.io/en/tf-mv2.1.6/releases/2.1.6.html * v2.3.1: https://trustedfirmware-m.readthedocs.io/en/tf-mv2.3.1/releases/2.3.1.html

Many thanks to everyone who contributed, reviewed, tested, and supported these releases.

Best regards, TF-M Team