docs: migration-guide-4.3: Add TF-M attestation issue

Add documentation describing a TF-M attestation issue that prevents
firmware-over-the-air (FOTA) upgrades between affected Zephyr releases.
Recommend a direct upgrade to Zephyr v4.3.0 to avoid attestation and
upgrade compatibility issues.

Signed-off-by: BUDKE Gerson Fernando <gerson.budke@leica-geosystems.com>

Author: nandojve

doc/releases/migration-guide-4.3.rst

@@ -534,6 +534,17 @@ Trusted Firmware-M
       confirming them with ``psa_fwu_accept()``. Otherwise, the images will roll back on the next
       reboot.
 
+* A compatibility issue was identified in the TF-M attestation procedure introduced
+  after the TF-M v2.1.0 release. As a result, systems using TF-M v2.1 cannot be
+  upgraded to any later TF-M version without encountering failures.
+  This limitation affects Zephyr versions using TF-M v2.1.0 through v2.1.2, specifically,
+  Zephyr v3.7 through v4.2, preventing seamless upgrades between these releases.
+  The issue was resolved in mainline TF-M as of October 25 and the fix is included
+  in Zephyr v4.3.0. Users are advised to migrate directly from any earlier Zephyr
+  release to Zephyr v4.3.0 or later to ensure full TF-M attestation functionality
+  and upgrade compatibility.
+  (:github:`94859`)
+
 * Support for automatically downloading MCUboot and ethos by CMake in a build has been removed,
   the in-tree versions of these modules will be used instead. To use custom versions, create a
   :ref:`west manifest <west-manifest-files>` which pulls in the desired versions of these